Similar to Mistaken for Gay, this is when a character is wrongly accused of cheating on his spouse or girlfriend because of a series of misinterpreted clues. Usually these clues look very suspicious (a bra left in his apartment, lipstick on his collar, a piece of Affair Hair, a romantic note) and the real story is hard to believe. The wrongly accused may protest "Wait! I Can Explain!" or "It's Not What It Looks Like!" If the spouse or girlfriend is another major character, the conflict will be resolved; if the love interest is a Girl of the Week, she may storm off, thus ending the relationship.
Shows aimed at kids also have a version where it's the kids who wrongly suspect that one of their parents is cheating on the other. Other variants include the love interest discovering that the would-be boyfriend thief is actually a relative, a member of an Incompatible Orientation, or in rare cases, even the wrong gender.
One notable property of this trope is that it can be used on shows that, because of their genre or their scrutiny by Moral Guardians, could never use a plot that involved actual adultery. But you can get some of the same benefits from a story where a character wrongly believes that adultery is going on.
- A cement mixer advertisement, based on an urban legend, has a married cement mixer driver come home to find a fancy car in his driveway, and sees his wife with another man. He fills the car with cement in a fit of rage, only to find the was giving them the car.
- In the State Farm "State of Unrest" commercial, a woman finds her husband on the phone with a (male) State Farm rep at 3am and assumes he's talking to another Woman. She grabs the phone and starts talking to him.
Husband: Yeah, I'm married. Does it matter?...You'd do that for me?...Really?...Yeah, I'd like that—
Wife: Who are you talking to?
Husband: It's Jake from State Farm. Sounds like a really good deal.
Wife: Jake from State Farm at three in the morning? *grabs the phone* Who is this?!
Husband: It's Jake from State Farm.
Wife: What are you wearing, "Jake from State Farm"?
[cut to State Farm office]
[cut to living room]
Wife: She sounds hideous.
Husband: Well, she's a guy, so...
Beldar: Correct I have a lifemate! Is that consequential? Hmm, ah...
- A variant of this ad instead features The Coneheads, with Beldar being suspected of infidelity by Prymaat due to the notion that no one would contact "Planet State Farm" at "0300 hours." The joke is, of course, these are the Coneheads we are talking about, so it doesn't go quite the way the normal version does.
Prymaat: With whom are you communicating?
Beldar: Jake from Planet State Farm!
Prymaat: Jake from Planet State Farm? At 0300 hours? *takes the phone* State your identity.
Beldar: It is Jake from Planet State Farm! Home of discount double-check.
Prymaat: Describe your apparel, "Jake from Planet State Farm."
Beldar: *hissing noises*
[cut to State Farm office]
[cut to living room]
Prymaat: Khakis? Explain.
Beldar: A dull Earthly garment covering male extremities.
Prymaat: *quietly surprised* Sounds most appropriate.
- A 90's commercial shows a couple kissing on a coach, until a woman calls telling the guy she'll be coming over. The girlfriend slaps him in angry and walks out. The woman who called was revealed to be a chubby maid with with a sultry voice.
Maid: (vacuuming) Hey sweetie, pick up your feet.
Man: (watching TV and drinking sully, over the noise) Thanks for coming!
- Forms the basis of some of the plots in Ah! My Goddess, when Belldandy suspects Keiichi is cheating on her. In the end it always turns out to be a Not What It Looks Like moment, or in Hild's cases, manipulating him and the goddesses in order to try to steal him away.
- Played for intense drama in Akatsuki no Aria. Shiroyuki-sensei is a married man who has Hot for Student feelings for the titular Aria, but would never cheat on his Ill Girl wife Kimie with her. Bad thing, Kimie died all alone in an hospital when he was trying to help Aria with her bad hand, so Kimie's family does think he was fooling around with Aria while his wife was on her deathbed. Naturally, Shiroyuki feels TERRIBLE when he finds out.
- Happens a lot in Baka and Test: Summon the Beasts to the two main guys, Akihisa Yoshii and Yuuji Sakamoto. In one hilarious incident, Shouko demands access to Yuuji's cellphone, and after she starts to strip him in order to find it, he gives it to her. She then finds a text written to him by Akihisa, asking if Yuuji would let him stay over at his place that night. She immediately assumes that they're in some kind of illicit relationship. Later the main characters go to his house for a study session (and to see why he didn't want to go home), and the two girls who like Akihisa immediately also start questioning him as to why there's women-related clothing and items in his apartment (which turns out to be his sister Akira's stuff, who's visiting him to make sure he's not goofing off).
Himeji: This bra isn't your size, Yoshi-kun...
- In Bakuman。, Akito Takagi, seeking ideas on how to write female characters, meets fellow mangaka Yuriko "Ko Aoki" Aoki, but keeps the meetings secret from his girlfriend Kaya Miyoshi out of fear that she would get jealous over him turning elsewhere for advice. While there, he meets his former classmate and academic rival, Aiko Iwase, who gives him a copy of her book with a letter inside. Miyoshi then discovers the letter and becomes quite upset until the misunderstanding is cleared a few chapters later.
- A Cruel God Reigns:
- Happens between Jeremy and Vivi in the earlier chapters. Jeremy is forced into having sex with Greg so that he will marry his mother Sandra, and eventually Vivi notices the subtle differences in Jeremy's reactions to her affection, his kissing, reactions to being touched, suspicious reactions to being asked, etc. Although Jeremy does actually cheat on Vivi, it falls into this troupe because it is against his will and it affects him very negatively, eventually ending in Jeremy killing Greg by Make It Look Like an Accident and Vehicular Sabotage . Jeremy tries both I Can Explain and Not What It Looks Like to try to keep Vivi as his girlfriend.
- Also happens with Lilia. Greg suspected that she cheated on him while the two were in Boston and that Matt is an illegitimate child.
- The first episode of Death Parade has an... extremely complicated example of this trope. The series takes place in what is essentially purgatory and the premise revolves around an Artificial Human who must decide whether people either get sent to an endless void or are allowed to be reincarnated. The first episode revolves around a newly wed husband and wife who died on their honeymoon. At first we're led to believe Machiko is a Gold Digger however a few moments later she explains to Takashi that he misunderstood everything. However it turns out she really did cheat on him, however only once and she regretted it. Then it's revealed that too was a lie. She never loved him and their unborn baby wasn't his. Machiko gets sent to the Void for their actions however the end of the episode implies she was actually lying about lying. She hated seeing her husband blame himself for killing their child so she pretended it wasn't his in order to have him rest in peace. Decim recognizes his mistake however it's too late to fix, and Machiko is cursed to all of eternity falling in an endless abyss.
- Dragon Ball: In a filler episode, a master thief named Hasky attacks Yamcha with a sword to try to steal the Dragon Balls he was carrying. Yamcha fends her off, but then his girlfriend Bulma arrives on the scene. Bulma completely misinterprets the situation due to the angle she is seeing them and thinks Yamcha and Hasky are making out. She angrily throws a crate at Yamcha's head and storms off, allowing Hasky to knock Yamcha out and steal the Dragon Balls. Even after Goku stops Hasky, Bulma remains convinced Yamcha was unfaithful.
- Dragon Ball Super: A jealous action star tries this on Gohan and Videl, managing to get a picture of a pop idol kissing Gohan. Videl sees through it instantly though, saying that she knows Gohan would never cheat on her, there must be some circumstances behind the photo, and how pathetic is the guy that he thought such a trick would break up her marriage?
- Chapter 97 of Kaguya-sama: Love Is War has Kashiwagi coming to the Student Council for help because she thinks her boyfriend is cheating on her with her best friend Maki. In something of a subversion, while her boyfriend wasn't cheating on her (he was asking for help about buying an anniversary present), Maki was trying break them up so she could have him for herself.
- Kimagure Orange Road:
- Used in one of the OAV's, Message in Rouge (And the manga story it was based on.) Madoka has an Heroic BSoD and runs away from home when she believes her beloved dad is cheating on her also beloved mom, staying in the Kasuga apartment when Kyousuke is home alone. It turns out Mr. Ayukawa was checking on the well-being of a co-worker who had a bad eye, and Mrs. Ayukawa knew it all the time.
- Played much more for laughs in the OAV that introduced Akane. She mistakenly believes Kyousuke is cheating on Hikaru with Madoka, goes on to give his "other woman" a piece of her mind... and is left starstruck by her.
- Kyo Kara Maoh!: Wolfram is always accusing Yuuri of cheating and Yuuri never is.
- Manami from Life mistakes her boyfriend for cheating when he's tutoring Ayumu. She gets her Japanese Delinquent lover to beat him up later.
- Chapter 14 of Love Me for What I Am starts with Suzu's boyfriend Haruto seeing him eating with Tetsu. Haruto gets the wrong idea and think that Tetsu is trying to steal his boyfriend.
- Happens in My Bride is a Mermaid when a series of events results in Lunar's father walking in on Nagasumi rubbing Lunar's ass. Everyone immediately assumes that he was cheating on San, including San herself. Despite the fact that this exact circumstance (mermaid gets wet, reverts to mermaid form, forcing Nagasumi to dry them off, only for them to turn human at the worst possible time) has happened to her.
- My Next Life as a Villainess: All Routes Lead to Doom!: Maria's ability to use magic led to rumors that her mother had an affair with a nobleman due to how insanely rare magic is among commoner. The truth of the matter is that no cheating had taken place, but her father eventual came to believe the rumors and walked out on the family.
- Naruto: Naruto Gaiden comes down to this. Sasuke's daughter Sarada worries that Sakura is not her biological mother, Karin is. She goes through a lot of trouble to find out the truth and even Naruto believes that maybe Karin is her mother. It turns out to be a misunderstanding. Sakura is Sarada's biological mother after all.
- One Planetes episode begins with Lavie seeing Fee talking to Director Dolf; as he's on a balcony a good distance away, he can't heard a word of it and assumes they have ulterior motives. (They're actually discussing Fee's possible promotion.) When he tells the rest of Debris Secton about this, they come to the en masse conclusion she's cheating on her husband. This lingers until Ai finally just asks Fee about it. Jump Cut to Lavie taking a roundhouse kick in the chest for having started the rumor.
- It didn't help that, previous to their work at Technora, Fee and Dolf were coworkers at a small firm, and thus are still friendly to each other in private.
- Surprisingly, Pokémon featured an instance of this in one episode — May's father Norman and the local Nurse Joy were actually setting up a fireworks display celebrating Norman and Caroline's anniversary. The English dub censored the plot by making it seem like Caroline and Norman were fighting, instead of doubts of fidelity being implied.
- In the chibi "Tenipuri Family" episodes of the The Prince of Tennis anime, Inui is mistaken for cheating by Oishi (his wife) when Ryoma tries on his mother's lipstick and later uses one of Inui's shirts to wipe it off, leaving a Lipstick Mark.
- Happens multiple times to Ranma from Ranma ½, almost always in a way that goes far beyond mere lipstick on his collar. A few examples:
- Caught in bed with a girl snuggled up to him, both of them asleep (the girl slipped into his bed while he was asleep).
- Caught with a girl attached to him like a barnacle while both of them are naked (she snuck after him into the furo as a cat and glomped him).
- Caught shoving a girl down onto a table while grabbing one of her breasts and shouting "Now give it up!" (No, seriously, it really isn't what it looks like.)
- Ironically, the one time he did want to be Mistaken for Cheating in order to get out of a commitment, he used a very literal Lipstick Mark (which he applied himself in female form) and it was casually brushed off by the girl in question.
- The entire student body always jumps to the conclusion that Ranma is cheating on Akane.
Girl #1: Don't just stand there, Akane.
Akane: What do you mean?
Girl #2: Ranma is making moves on another woman again.
- In the manga version of Shaman King, Anna mistakes Yoh's new Oracle Bell as a pager that a girl gave him. It doesn't help his case that he had a long black hair on his clothes from Silva. In the game Power of Spirits, this is taken further when Meril, a girl Yoh had never met until this point, walks in and hugs him.
- Thanks to a misinterpreted conversation eavesdrop in a chapter of The Tyrant Falls in Love, Morinaga comes to believe that Souichi is having a sexual relationship with Isogai. (The truth is far more embarrassing for Souichi: he was blackmailed by Isogai, who discovered the relationship between him and Morinaga, into singing the Doraemon theme song on karaoke nights at Isogai's place.) One part that does not follow this trope is the discovery of hickeys on Souichi's neck which Morinaga takes as solid proof, forgetting that he made them himself several days ago.
- Shi from Wandering Son mistakes Yuki for cheating with one of the protagonists, Takatsuki, in his first appearance; she's touching him rather suggestively on the face. The creepy part is that, though Yuki would never harm Takatsuki, she is in her mid-twenties at youngest, and Takatsuki was only eleven... And though assigned female at birth feels that he's actually more like a boy, though neither Shi nor Yuki knew that (though Yuki seemed to have guessed).
- In The World God Only Knows, Elsie passes herself off as an illegitimate daughter of Keima's father (who is constantly away on business), which leads to his mother angrily calling her husband up. Later on, Haqua does the exact same thing, which leads to another angry call to a now very confused husband.
- Lampshaded in Yu Yu Hakusho, when Keiko misunderstands Yusuke's relationship with Botan, who is just a friend and a partner to the spirit dectective.
Yusuke: Wait, Keiko! It's not what you think!
Keiko: How do you know what I'm thinking?
Yusuke: Because I know what it looks like!
- One Archie story had Archie's mother borrow his jacket and accidentally leave a tube of lipstick in the pocket. Betty and Veronica later borrow Archie's jacket and find the lipstick. They think that Archie is seeing another girl because the lipstick isn't either of their brands, and angrily confront the baffled Archie. Betty and Veronica both dump Archie, but then they realize that this will just make him go after the girl they think he's seeing now. They both come back and smooch Archie to show that they're better than the competition. The story ends with Archie's mother realizing what she did and apologizing if she caused him any trouble, but a love-dizzy Archie just tells her to cause as much of it as she wants.
- In Robin Tim gets forcefully kissed by a Stalker with a Crush and his girlfriend Stephanie, in an out of character moment used to propel her into the role of Robin and kill her off, sees it, decides he's cheating on her and refuses to talk to him for a couple of months.
- Mary Jane Watson's Aunt Anna once tried to get her to face the "truth" about Peter Parker's apparent infidelity, what with all his sneaking around at odd hours and missing commitments with the flimsiest of excuses; this aggravated MJ enough to evoke a Sarcastic Confession: her husband was really Spider-Man.
- The villain Queen kissed a defeated Spider-Man. Photos and news of the kiss quickly spread around New York, about how the two foes were battling before suddenly Spidey kissed Queen. Even Aunt May and Mary Jane thought that Peter was the one who kissed her, instead of the other way around.
- Shock SuspenStories:
- A story in #11 called "Three's a Crowd" had a paranoid man believing his wife was cheating on him with his brother and he murders them both. It turns out they were being secretive because they were planning a Surprise Party where the husband would find out she was pregnant.
- Another story in the same comic, "The Tryst," was based around a man being extremely possessive of his much younger Trophy Wife. When she mentions a new male friend, the husband believes she is having an affair, and shoots her friend dead from a distance. The friend turns out to be a young orphan boy she had been caring for because her husband refused to have a child with her.
- Superman had to deal with this in one story when Lois discovered a pair of Lana Lang's panties in their bed which the jealous Lana had planted during her last visit.
- When Cir-El, a new Supergirl, makes her first public appearance and introduces herself as "Superman's daughter", she leaves out some vital details to her story (that Lois Lane is her mother and she comes from the future) that cause Lois to mistake her for a lovechild born from Superman having a tryst with Wonder Woman.
- Jimmy Olsen has been known to be Disguised in Drag on more than one occasion. After one such example, though, Jimmy got read the riot act by Lucy Lane. Turns out Lucy found in his apartment the purse, perfume and jewelry that were part of the masquerade lying around his apartment, but she thought he was dating someone else behind her back.
- In Supergirl Vol 1 #2, Linda — the eponymous heroine — is doing mouth-to-mouth resuscitation to a drowned man. One of her classmates who flirts with her earlier meets them and thinks she is cheating on him... even though she is dating nobody.
- In the sixth issue Supergirl is hugging gang leader Ricky in gratitude for listening to her when Loretta — Ricky's girlfriend — walks in on them and thinks her boyfriend is cheating on her with Supergirl. However it was a totally innocent act.
- In Girl Power, Cassie Sandsmark -alias Wonder Girl II- walks in while Kara and Superboy are having an argument and assumes that the two are engaging in foreplay. She attacks Supergirl and loses, but the misunderstanding is cleared up.
Supergirl: Whatever you thought was going on, Cassie— wasn't. I came looking for someone I could talk to.
- One The Simpsons comic book story has Homer repeatedly moaning "Selma" in his sleep, which (along with a few other events) leads Marge to the improbable conclusion that Homer is cheating on her with her sister. At the end of the story it's revealed that Homer has actually been dreaming about a pork festival in Selma, Massachusetts.
- In one comic, The Joker decides to mess with a rehabilitative Two-Face by suggesting that his girlfriend and best friend Bruce Wayne are fooling around behind his back and want to keep him locked up in Arkham. To give it one final push, Joker has one of his goons make a fake newspaper article that Bruce and the girlfriend were getting engaged and slipped it to an already suspicious Two-Face. Two-Face then loses it, escapes from Arkham, proceeds to kidnap his girlfriend and attempt to murder Bruce.
- Ultimate Spider-Man: Liz is drunk at a party at Long's house, and tries to hook up with Peter. He tries to get her away from him, but too late: Mary Jane shows up, and saw it.
- A series of FoxTrot strips has Andy convinced that Roger is cheating on her when he's actually at work. ("Listen — hear that squeaking? You know how my chair squeaks." "Sounds like bedsprings." "Fred, get in here and talk to my wife.") In the last strip, she apologizes for being paranoid and they hug...at which point she plucks a hair from his jacket and asks whose it is. (No, Roger wasn't cheating; he's just balding.)
- Fred's response to being called over is "Not again...", implying that Andy does this with some degree of regularity.
- One comic in Andy Capp has Andy returning home late and apologizing to his wife. He comments that she hasn't said anything for three nights, and jumps straight into assuming the worst.
Andy: WHO IS HE?
- Requiem for a Loud has Lincoln trying to tell Ronnie Anne the truth about his condition. He's almost close when Cristina comes in. In that moment, RA thinks that he is getting together with Cristina when he isn't. It is soon resolved.
- A Pikachu in Love has an odd platonic, 'best friend' version. When Ash wakes up the morning after Pikachu spent the entire night up with Pichi, he's confused as to why his friend is still sleeping when he's usually up at this hour. Deciding not to disturb him he takes Bayleef fishing with him instead. Unfortunately, Pikachu wakes up a few seconds before they leave, and wonders why Ash didn't take him instead. This is what gets Pikachu to really consider how strong of a bond with Ash he actually has...
- Evangelion 303: When Mandy perused her girlfriend's Secret Diary she read many entries where Jessika revealed that she had a crush on her teammate Asuka and described what kind of things she wanted to do with -and to- the red-headed girl. Mandy thought Jessika had been unfaithful and she even accused Asuka from being a home-wrecker, but Jessika never cheated, and those diary entries were merely her fantasies.
- Higher Learning: After partially overhearing a conversation between Asuka and their teacher where he apologises for overstepping his boundaries and she replies it was not his fault, Shinji thinks Asuka is cheating on him. In reality nothing happened between them.
- In Smallville this fanfic, Lex Luthor is caught "cheating" on Clark Kent with Superman, mixing Mistaken for Cheating with Two-Person Love Triangle in a PR disaster.
- In Through a Diamond Sky, this kicks off the plot. Jordan thinks that Kevin's secretive behavior, bizarre references, and long periods of no accountability are proof she's married a cheater - again. (He's husband #2). While it's true that he's up to a lot of very strange things in cyberspace, an affair isn't one of them.
- In the Ben 10 Hero High: Sphinx Academy, Ren suspects this of Ben when she has noticed him hanging out with Julie several times, though more often than not he is getting help from Julie to get a gift for Ren for their upcoming anniversary. It doesn't help that Susan, one of the Big Bad's lackeys and instructed to cause tension between the couple to slow them down, is the one encouraging the idea.
- In The Many Secret Origins of Scootaloo, Mrs. Cake catches Fluttershy giving Twilight Sparkle mouth-to-mouth, and immediately spreads the word that Twilight is cheating on Rainbow Dash. Twilight and Rainbow Dash aren't even dating.
- The Reading Rainbowverse has a... complicated example, in that Big Mac thought he'd made it clear that he'd broken up with Fluttershy, but Fluttershy didn't get the memo, and the fact that Mac was interested in a relationship with a changeling of all things just made the situation more awkward. It ended up with Fluttershy going on a drunken rant and then getting suplexed off a dragon, after which she spent a couple weeks in the hospital high on morphine...
- Pops up from time to time in Miraculous Ladybug fanfiction with the complication of the series' Love Square: ie, one of the heroes will be suspected of cheating on their partner with... their partner.
- In the post-reveal fic Glaze, Alya figures out from a few clues that Adrien and Chat Noir are one and the same, and her immediate reaction is to call him a lying cheating asshole for kissing Ladybug behind Marinette's back. It takes her a minute (and Marinette walking in, hearing her accusation and addressing Adrien as Chat) to realise that Marinette is Ladybug.
- The fic Odds Are That We Will Probably Be Alright, is set in a future where Marinette and Adrien have been dating since high school and are engaged to be married. However, both have become convinced the other is cheating on them, due to frequent suspicious disappearances and flimsy excuses, but neither of them can say anything to the other without risking their own secret, forcing them to confide in their respective best friends and their partners. When Nino and Alya get tired of their complaining, they force them to confront each other about it, leading to a heated argument where both become angry at the other's accusations. It gets to the point where Adrien decides to clear himself by admitting to being Chat Noir... but his wording - "Im fucking Chat Noir, okay? Thats why I have to leave." - predictably has the exact opposite effect, getting Marinette, Alya and Nino furious at him until he transforms to show them the truth.
Alya: I cant believe we had to spend months with you two thinking you were cheating on each other with each other.
Nino: Not with each other. Adrien did say hes been cheating on Marinette with himself.
- Another post-reveal story, Scandalous! has Alya walking in on Marinette kissing Chat Noir, followed a few days later by Nino catching Ladybug kissing Adrien. Fearing that her friends' relationship is falling apart, Alya brings them together for an intervention. However, Adrien and Marinette manage to come up with the excuse that they had a bet about who could kiss their favourite superhero first - Marinette won, but she said that Adrien could go through with the kiss if he ever got the chance. Alya almost buys it, only to instead start to suspect that her friends are Ladybug and Chat Noir.
- Played more seriously in Back To Us. Alya comes to suspect something's going on with Nino and Marinette after overhearing and misinterpreting a conversation between keeping their superhero lives from her, leading her to break up with Nino right when he was about to propose. She figures out the truth before too long and they get back together.
- Earlier, the host of the Christmas Ball is akumatized because he believes his supermodel wife is unfaithful, having a lot of private meetings with other men, including Adrien. In reality, she was cancelling arrangements so that she could quit modeling and dedicate her time to their coming baby.
- I Saw Mummy Kiss Chat Noir features an Adrien and Marinette who are Happily Married with three wonderful kids and another on the way. Unfortunately, the eldest of their kids, one Emma Agreste, sneaks out of bed one night and sees her mother kissing Chat Noir. Cue Adrien and Marinette wondering why their daughter suddenly and violently loathes all things Chat Noir. The fic ends with the younger Agrestes walking in on Adrien kissing Ladybug.
- A variant is present in The Seven Misfortunes of Lady Fortune. Alya is actually happy that Adrien spent the night with a girl instead of wallowing in memories of the long dead Marinette... but goes absolutely berserk upon hearing a noise from upstairs, and realizing the two must have been defiling the late girl's bed. Of course, she later learns that Marinette is actually alive and was that very girl.
- Done very bleakly in The Keys Stand Alone: The Soft World when Paul finally confesses to the others that after he came home from C'hou in With Strings Attached, he had a tough time adjusting to being normal again, and for a while was terrified to even touch Linda and his kids. She decided he'd disappeared for those four days with another woman and now hated her. Given that the truth was, as Paul put it, so fucking insane, it took him quite a while to both get over the sense that he would kill her if he hugged her and to convince her of the truth.
- In A Complete Turnabout Phoenix gets a pink letter from Maya leading to the belief that he's cheating on Iris. The letter wasn't a Love Letter and it was pink because of Maya being Maya. Ironically Iris herself doesn't seem to care about the letter.
- In Supergirl (2015)/The Flash (2014) crossover Call Me Kara, Kara and Barry's first fight occurs when she walks in on him and Iris hugging after sharing lunch. Of course, she was already upset, given that that day was the anniversary of her planet exploding.
- In Persona EG, Sunset Shimmer pins Flash Sentry against a wall and forces a deep kiss on him in front of Twilight, reducing her to tears. Turns out someone took a picture of the kiss and posted it to Canterbook, and by the end of the day everyone has seen it and thinks Flash is cheating on Twilight with Sunset, even his friends. Luckily he is able to clear everything with them by sitting down and talking to them, saying she assaulted him and she was the one who kissed him.
- Prodigal Son: When Astrid and Fishlegs start collaborating on figuring out the nature of Hiccup's absence, her mother starts to suspect that they are having affair.
- In Tony's Girl, Laura Barton accuses Clint of having an affair with Wanda, because why else would he come out of retirement and abandon his family to help a former HYDRA agent if he wasn't fucking her.
- Invoked in The Ripple Effect in order to get Jerrica to run to Riot. At Jerrica and Rio's wedding, Minx drugs Rio, takes him into a room, and makes it look like they slept together. Jerrica catches them and gets the wrong idea. Luckily, Stormer noticed what Minx did and spoiled The Stinger's plot.
- Máscara Sonreindo: When Kagami tells Misao that Ayano has a boyfriend, Misao thinks that Ayano is cheating on her. In reality, Ayano just made up a boyfriend to stop boys from hitting on her.
- Of arcane energy and missing hearts is rather intricate one. In the fanfic, Taako's soul is switched with Damian, a tiefling. As such, his soul is now in a different body. Once Kravitz figures it out, he immediately kisses Taako after Damian (in Taako's body) is knocked out. Of course, this is at the moment when Lup comes in, and finds her "brother" out cold with his boyfriend making out with a total stranger. She almost burns the two to ash before her real brother talks sense to her.
- Played for Drama in Flowers Drenched In Vodka. A drunken Eli reacts so negatively to seeing Umi exit her house that she beats her girlfriend Hanayo so hard that she gets sent to the hospital.
- In Lady and the Tramp III: Family Troubles, Lady gets suspicious of her husband Tramp when his old fling Peg reunites with him. She sees Tramp sneak out one night and smells Peg on him when he comes home the next morning. Despite Tramp insisting that they just talked, Lady doesn't believe him. When he runs after their runaway son Scamp, Lady worries that Tramp plans on leaving town with Peg.
- Roadside Assistance: Yang sees Neptune kissing Sun and is enraged that he's cheating on his wife Weiss. She doesn't know that Weiss encourages Neptune to date because their relationship isn't romantic.
- In the old (NSFW) fic With Three You Get Eggroll, Hermione mentions almost killing Lupin the first time she caught him and Tonks spicing up their love life the obvious way.
- Restraint: Invoked. Azula lied to Ty Lee and stated that she cheated with Katara. She keeps up the lie for years because it's easier than explaining the truth.
- In The Loud House fanfic Boys And Girls, Lori thinks Lincoln is dating Ronnie Anne when he's in a suit, claiming he's going to go to a fancy restaurant, but not with Ronnie Anne. Really, he's [[folder: pretending that he's going out with Hugh.]]
- The Incredibles: Helen finds one of Mirage's hairs on Bob's suit, then overhears the second half of their phone conversation before he suddenly leaves on a "business trip." It's never explicitly mentioned, but her thoughts are pretty clear. The outtakes, meanwhile, include scenes where she outright asked him if he was seeing another woman. To make matters worse, when she does finally find Bob inside the villain's lair, it's right as he's hugging Mirage (just out of pure gratefulness for helping him, but Helen doesn't know this). Helen promptly punches Mirage out cold.
- Strange Magic plays with this - one of the first scenes is of a fairy princess catching man she was about to marry kissing another woman (on their wedding day), but another character later describes the situation as a "misunderstanding" - her charismatic ex convinced everyone, including her father, that either he didn't really cheat or it was a minor lapse in judgement and won't be repeated.
- Invoked in Andhadhun. Simi sets it up so that Sofie will believe that Akash is sleeping with Simi by poisoning him and opening the door partially undressed when Sofie turns up at Akash's place.
- In Big Fish, when Will meets Jenny, he rather abruptly blurts out the question of whether she and his father, Edward, had an affair. (Answer: no, but not for lack of her trying.)
- Bridget Jones: The Edge of Reason was made up of this from poor communication. Bridget becomes paranoid that her boyfriend Mark Darcy and his younger, thinner, and composed Brainy Brunette assistant Rebecca were having an affair, and during Bridget's stint in a Thai prison he is revealed to think she got back together with his ex-friend Daniel. The couple gets back together in the end.
- In the Soviet comedy The Diamond Arm, a man named Semyon accidentally gets an orthopedic cast full of diamonds placed on his arm during a trip to Istanbul by smugglers working with The Mafiya, assuming him to be a courier. Upon arrival back home, he immediately goes to the police, only for them to use him as bait for the larger organization. His wife starts getting suspicious about strange absences and a gun she finds in his things, but he tells her he is on a "special mission". It gets worse, when their apartment building superintendent tells her that her husband's behavior is shameful, pointing out that she wouldn't be surprised if he's seeing another woman on the side (in the original script, she suggested that he might be secretly Jewish, but the line was overdubbed in post-production due to the Censorship Bureau). The bad guys hire an attractive blonde to seduce Semyon and put a sleeping pill in his drink. Just then, Semyon's wife (who has found the woman's note with her address) and superintendent burst in and see Semyon seemingly drunk (he's actually suffering the effects of the pill) with a half-naked woman dancing for him. The blonde shifts blame onto Semyon with a line that has since become famous, "It's not my fault, he came himself!" The next morning, Semyon wakes up in his apartment to find his wife and kids gone, with a note telling him that, now that she knows what his "special mission" is all about, she is moving back in with her mother and taking their kids with her. Fortunately, by the end of the film, the cops explain the truth to her, and she comes back.
- In the film Easy Living, everyone thinks Mary Smith is J. B. Ball's mistress, because he gave her a sable coat and bought her a hat to match it.
- In Enchanted, Giselle, just coming out of the shower, trips and falls on top of Robert, who had tried to catch her. Then Nancy walks in...
- In Finding Neverland, James's wife and several others believe that James and Sylvia are having an affair when he spends more hours with her and her sons than at home. In reality, he only saw her as a platonic friend. The wife eventually realizes the truth, but they still wind up divorcing, as she feels (perhaps correctly) that he cares about said friendship more than he does about their relationship.
- In The Fly (1986), just as Seth and Veronica are celebrating his perfecting the telepods she discovers a package left at his loft by her editor — and jealous ex-lover — Stathis, which reveals that he intends to have his magazine jump her on the story of Seth's invention (which she is writing a book about). She leaves to confront him, and not wanting to get Seth involved in her personal drama just says it has to do with "residue" she has to "scrape off [her] shoe". However, Seth realizes that "'residue' means old boyfriend" and assumes she is cheating on him. He ends up getting drunk and decides to go ahead with the final step of the telepod project: teleporting himself, unaware as the timer ticks down that a fly is in the pod with him. A few hours later Veronica returns and she and Seth quickly reconcile as she explains everything — but the audience knows their happiness is already doomed, as strange hairs are sprouting from a wound on his back...
- In The F Word, Chantry surprises her boyfriend, Ben, by taking him up on his open ticket to Dublin where he's doing work for the United Nations. When he shows up, he's drunk and stumbling arm-and-arm with an attractive Brazilian co-worker. He maintains that it's entirely innocent, that they just drank a bit too much and were both headed back to their respective rooms in the shared housing. Nothing in the film contradicts his narrative.
- In Gone with the Wind, Scarlett pines over Ashley Wilkes, who married his cousin Melanie but courted her before then. Scarlett frequently urges him in private to run off with her, and Ashley is tempted but refuses. Then when Melanie is dying, she appears to tell Scarlett that it's alright to date Ashley after she's gone. Scarlett, however, is too upset to even think about that and falls crying into Ashley's arms... which several visitors spot and think Scarlett is Romancing the Widower.
- Earlier in the film, after agreeing to be friends despite the years-long UST, Scarlett and Ashley hug each other, only for Ashley's sister to walk in at that exact moment and get the wrong idea. The one person who believes in Scarlett's innocence is, ironically, Melanie.
- In The Hand That Rocks the Cradle, the nanny gets the husband to plan a surprise party for his wife with their friend, who is the only one around the husband who smokes. When the wife finds her friend's lighter in her husband's suit jacket, she thinks he's having an affair, which she calls him out on with the next room full of party guests.
- Invoked in Hangmen Also Die!. Mascha and Dr. Svoboda make it seem like they're having an affair to hide what they're really up to (Dr. Svoboda assassinated Reinhard Heydrich and Mascha helped him get away with it).
- Horrible Bosses 2: When Nick, Dale and Kurt start arguing about whether or not Dale should have sex with Julia and risk jeapordizing his marriage so that she doesn't call the police on them, Dale's wife Stacy finds them, overhears everything, and runs off thinking that her husband is cheating on her.
- Used as Mind Screw in Internal Affairs (1990). Dirty Cop Dennis Peck knows the protagonist, Internal Affairs officer Raymond Avila, is following him, so he arranges to meet Avila's wife in a cafe where he discusses some innocuous business. He then assaults Avila in an elevator, taunting him about having sex with his wife and throwing a pair of panties in his face (which don't even belong to her).
- I Saw What You Did: Because of the persona Libby adopts when phones Steve, she assumes that Libby and Steve are having an affair. She attempts to drive Libby off as a potential rival.
- Played for Drama in It's a Wonderful Life, where one of the many, many things that causes George Bailey to hit Rock Bottom is his co-workers starting rumors about him and his friend Violet Byck after they witness him lending a large amount of money to her pro bono. In reality, of course, he did it because he's just that danged nice.
- Jack Strong comes home late, if at all, generally neglects his family, so his wife starts suspecting an affair.
- In Knocked Up, Pete is making up lies about work and sneaking out of the house so that he can go see his fantasy baseball league.
- In Lethal Weapon 4, Riggs gets suspicious about Murtagh because his large expenses like on house remodeling seem impractical on a cop's salary. He eventually confronts Murtagh about it — in the middle of a firefight — where Murtagh is initially evasive about where the money's coming from before he eventually relents and asks if Riggs knows Ebony Clark, who writes what Riggs calls "cheesy sex novels".
Riggs: Wait, are you boinking her?Murtagh: What, no! Trishnote is Ebony Clark!Riggs: Oh! (thinks for a moment) You are boinking her!Murtagh: ...Yeah, I guess I am!
- Mabel's Blunder (1914) involves Mabel getting jealous after seeing her fiance hugging an attractive woman. The woman turns out to be his sister.
- Subverted in the Brazilian movie Meu Tio Matou um Cara ('My Uncle Killed a Guy') Éder finds a series of pictures that seem to indicate that his girlfriend Soraya cheated on him with Kid. She then explains to him that he looked at the pictures in the wrong order, and they tell the story of a perfectly innocent afternoon. Later, the protagonist Duca mentions to a friend that the sun's position in the sky don't match Soraya's story, and Eder was right after all.
- In Mystic Pizza, Daisy (a poor Portuguese Catholic girl) sees her love interest Charles (a wealthy WASP guy) talking to a very attractive woman at a party. Consumed with jealousy, she persuades a lobsterman to dump his entire day's catch into Charles's expensive convertible sports car. Daisy then discovers that the woman Charles was talking to was in fact his cousin, leading to a memorable exchange:
Daisy: I fucked up.
Charles: Yeah... but you gave it a 100% effort!
- Humorously inverted in The Naked Gun 33 1/3. Lt. Frank Drebin first tells his wife Jane he's seeing another woman as a cover story, then Jane realizes that he's actually returned to his work as a detective despite agreeing not to.
Frank: I swear, it's another woman!
Jane: Oh, I wish I could believe that!
- In Never Weaken, Harold Lloyd sees his girlfriend hugging another man who says "I'll marry you right away!" This sends Harold into suicidal despair. Unbeknownst to him, the other man is her brother, a minister, who is saying that he'll officiate her wedding to Harold.
- The main plot of Nothing to Lose is kicked off when the protagonist thinks his wife is having an affair with his boss and decides to rob the company in revenge. The evidence is seemingly incontrovertible (the boss' cufflinks are on the table, and they are going at it in the bedroom), but if he'd actually tried confronting them, he'd have found out they were relatives he wasn't told were visiting (and had a sudden case of the randiness). And the cufflinks had been there for months ever since the guy lost them during a party.
- At the end of Pirates of the Caribbean: Dead Man's Chest, Elizabeth passionately kisses Jack, not knowing that her fiance Will is watching. She was actually distracting Jack so she could handcuff him to the ship.
- In the film Shall We Dance?, a woman becomes suspicious of her husband when she realizes that he's displayed the same traits that a friend's cheating husband is—late nights, distraction, etc. As it turns out, while the husband is bored with his life and having a mid-life crisis, he isn't cheating on her, he's taking dance lessons. However, the wife is still concerned about the possibility of him having an affair with one of the dance instructors.
- Inverted in The Shop Around the Corner: Mr. Matuschek knows his wife is cheating with one of his employees and comes to the conclusion that it is Mr. Kralik. It's really Mr. Vadas.
- Short Cuts zigzags the trope with extramarital lovers Gene Shepard and Betty Weathers. Betty has another boyfriend, Wally, with whom she is planning to spend the weekend, and has roused Gene's suspicions with a flimsy cover story. He tries to call her, but her soon-to-be ex-husband Stormy answers the phone instead and engages in a bit of Relationship Sabotage by shouting at Betty to put her panties on. That evening, Gene shows up at the house to see Stormy's car parked in the driveway and Stormy himself in silhouette through the bedroom curtains (unbeknownst to Gene, Stormy is instead destroying the contents of the house as an act of revenge against Betty while she is away with Wally). The enraged Gene throws a rock through the bedroom window and goes back to his wife.
- In Smiles of a Summer Night, Count Malcom barges in on Fredrik wearing the Count's nightshirt and robe at Desirée's place. Fredrik had earlier fallen into a large puddle of water and changed into the only dry clothes available.
- In the film Stars And Stripes Forever two members of Sousa's band (female singer and male Sousaphonist) are secretly married. When the Spanish-American War breaks out he reenlists, and they spend his last night before shipping out holding each other in an Italian restaurant. The restaurateur suggests that they should get married so they'll have a place to be together. "Oh we are married. That's why nobody can see us." After they leave, the restaurateur tells his wife that the couple should divorce their respective spouses and marry each other since they obviously love each other so much.
- That Lady in Ermine had this, due to Executive Meddling. Angelina's husband thinks she slept with the Colonel to make him leave (it was the ghost of her ancestor in a dream, convincing him to leave).
- An odd example in Top Hat. Dale has confused Jerry for her friend's husband, Horace. Jerry loves Dale and Dale is convinced he's trying to have an affair with her.
- Trading Places: Clarence Beeks pays a hooker, Ophelia, to act like she's involved with Louis Winthorpe while he's reconciling with his fiancee Penelope, to further sabotage his life. However, Ophelia soon takes pity on Louis, so she takes him in and later falls in love with him for real.
- In Transformers: Revenge of the Fallen, Mikaela walks in on Sam apparently sharing a passionate moment with an attractive co-ed, and storms off in a huff as Sam desperately protests that it's Not What It Looks Like. Said co-ed is actually a sexually aggressive Decepticon Pretender trying to get at the data embedded in Sam's head; the instant Mikaela leaves, the Pretender gives up on the Fake-Out Make-Out and starts attacking Sam properly.
- On White Chicks, Marcus's wife thinks he is cheating on her while he and Kevin were undercover as famous female while twins Brittany and Tiffany Wilson and staying at a hotel hanging out with the girls' friends. She overhears one of the twins' friends on the phone and catches him at the hotel room with "Tiffany" (actually Kevin in disguised).
- Occurs in Who Framed Roger Rabbit, when Jessica Rabbit visits Eddie Valiant to ask for his help with her case. On the line "I'm desperate Mr. Valiant, can't you see how much I need you," Valiant's girlfriend walks in. It doesn't help that his pants are down as well.
- When Lucy announces that she's pregnant in Written on the Wind, Kyle assumes that Mitch is the father due to his own fertility problems.
- A man is taking some time to get home, so his wife calls her mother. "He's cheating on me, I just know it!" "Now, dear, why do you always assume the worst? Maybe he had an accident!"
- Turns up regularly in the works of P. G. Wodehouse, often on the most hair-triggered and flimsy of pretexts.
- The Alice McKinley Books has Alice think her stepmother, Sylvia, is cheating on her father a few times. When she learns that Sylvia's ex is going to Chester, where Sylvia is currently working as an exchange teacher, for Christmas, Alice thinks she's cheating and will continue to see him, even after getting married to Ben. Sylvia tells Alice that she had no idea that her ex was going to do this and sent him packing. Another time, Alice saw Sylvia getting out of her ex's car and tried to avoid thinking this. Sylvia says that she was playing tennis with some friends and her ex was substituting for someone.
- In Honore D'Urfe's LAstrée the shepherd Céladon is shown to his love Astrée while he is reciting poetry to another by a jealous suitor looking to break them up. Despite the fact that Astrée herself had told Céladon to pretend to romance another to hide their relationship because their parents disapproved she thinks he was cheating on her and banishes him from her sight, leading him to try and drown himself in the river.
- In A Brother's Price, Jerin manages to mistake himself for cheating - when he can't remember a certain period of time, he fears that he cheated on his fianceés in that time, as he was there with a woman, and can't recall what, exactly, happened, only that it was a compromising situation. Turns out the mysterious strange woman is, in fact, one of his wives-to-be, and she cheerfully tells him that, if he thinks that was sex, she will have to give him The Talk.
- Chalion: A retroactive variant comes up in the backstory of Paladin of Souls. The cover story of espionage and bribery used to explain Chancellor Arvol dy Lutez's death in the dungeons of the royal castle some 16 years back was fairly transparent if one thought it through, so many (including the Chancellor's son) concluded that he had seduced the King's young wife and been caught out.
- The 16th Century Vietnamese Collection of Strange Tales has a story where a man, after coming home from the war, got rejected by his three-year-old son who claimed that 'his real father' always 'appears every night, stands when mother stands, sits when mother sits'. The husband thought his wife was unfaithful to him and kicked her out of the house without waiting for an explanation. The wife, in despair, drowned herself in a river. It wasn't until night came and the son pointed at his father's shadow on the wall, exclaiming 'That's my father!' that the husband realized that his deceased wife, who was just trying to calm their son (as he missed his father who was away at the war) with a white lie, had been innocent after all.
- In The Color Purple, until the day she died Corrine thought that her husband was cheating with his friend Nettie. This is because Corrine's adopted children have a Strong Family Resemblance to Nettie. As it turns out, her kids are the biological children of Nettie's sister Celie. Corrine refused to believe Nettie and thought she was lying about being their aunt.
- In one of the Confessions of Georgia Nicolson books, Georgia believes her mother is having an affair with the builder (apparently not true, her mother just liked to flirt with him.) Leads to a humorous incident where Georgia skips school to spy on them, but they open the door and she falls through it, forcing her to pretend she had been sent home sick.
- Subverted in Reginald Hill's Dalziel and Pascoe novel Death's Jest Book, in which Sgt. Wield gets into a paternal relationship with a rent boy that sure makes it look like he's cheating on his partner—even Dalziel thinks so—except that he isn't. Ironically, Wield's partner is the one who hangs a lampshade on the situation by pointing out that he has complete faith in Wield's motives.
- In Flawed, after escaping Logan's shed and being tormented all night, Celestine runs into her boyfriend Art and her sister Juniper. As this came after she had a fight with Art, her immediate reaction was to assume they were both going out behind her back. Juniper, however, later insisted that they were just friends who bonded over how worried they were for her.
- In Harry Potter and the Order of the Phoenix Cho gets this impression of Harry on their date, thanks to his poor choice of words in describing his meeting with Hermione later.
- In House of Mirth, Lily Bart is unfortunately—and wrongly—cast in the role of the "other woman". Once by a so-called friend who is trying to cover up her infidelity, another time by a man whose advances she has rebuffed.
- Hurog: In Dragon Bones, Erdrick thinks his brother Beckram is getting himself in danger by having a secret affair with the (married) Queen Tehedra. Turns out, no, Beckram was asked to share her bed by no one else than the king. (Who seems to prefer young men, anyway.) So, yes, he is sleeping with her, but it is not cheating.
- In Jinx High by Mercedes Lackey, Deke decides that the reason his father and Diana Tregarde are spending time alone together is that they're carrying on an affair. The real reason is to track down the mystical danger that wants Deke for lunch. To be fair, Deke wasn't aware of his own mystical abilities until late in the novel, and certainly wasn't aware that his parents had been part of Diana's Scooby Squad in their college days.
- In a Nancy Drew/The Hardy Boys Supermystery novel, Frank was half-carrying Nancy across a parking lot (she'd sprained her ankle), when they encountered her boyfriend Ned Nickerson. Already ticked off, he was even more so when she declined his offer of a date that evening, as she and Frank had to work on their case, thus confirming his incorrect suspicions that something was going on between them. The subversion here is that Frank and Nancy were quite attracted to each other throughout this Crossover series, so Ned's discomfort with their friendship wasn't entirely unjustified.
- Used tragically in Needful Things. Fiancées Lester Platt and Sally Ratcliffe are led to believe that each is cheating on the other. Lester beats her unwitting suspected lover half to death before being killed by the police, while Sally hangs herself in her closet.
- Happens with Denise and Spade in the Night Huntress books when she's told that "the vampire" is in a bedroom with another woman. She furiously pounds on the door only to find she's got the wrong vampire.
- The Parasol Protectorate: This becomes a major plot point when the wife of a werewolf (which are infertile in this setting) turns out to be pregnant. The wife in question is Alexia Maccon, a walking Power Nullifier who turns her husband mortal while in physical contact with him. Which she had to be during conception.
- The Quorum: The best and longest-lasting romantic relationship in Neil's life comes to an abrupt end after he steps into a pub for a quick drink with an old friend, only for a series of unfortunate accidents to result in him faceplanting into a compromising position with a young lady just as his girlfriend comes in to see where he's got to. She refuses to believe that it's just an accident, and in a way she's right: the whole thing was carefully orchestrated by the old friend, for an ulterior motive Neil doesn't find out about until much later.
- Red Dwarf: Better Than Life: Lister, who has been enjoying a happy fantasy life with a wife and two kids, is suddenly shunned in disgust by his entire community when a very obvious prostitute shows up looking for him, despite his insistence that he's never met her in his life. It's actually Rimmer in said prostitute's body.
- Septimus Heap: When Sally Mullin sees Silas and Marcia fleeing from the Custodians she thinks they are eloping. Sally also thinks Jenna was conceived by Sarah in an affair because Jenna doesn't look like Silas or Sarah (Jenna is actually secretly adopted).
- Southern Fried Rat and Other Gruesome Tales: An anthology collecting a number of stories based on varied urban legends, including The Solid Cement Cadillac, in which a perpetually suspicious husband, who drives a cement mixer and comes home to check on his wife one day, finds a brand new Cadillac in the driveway. Sneaking up to the house, he sees her in the kitchen, talking with another man. Assuming she's cheating on him and that the unfamiliar car is the man's, he fills the Cadillac with cement and drives off. When he returns home that evening, he finds his wife in tears, and learns she had bought him a Cadillac as a surprise, only to have someone fill it with cement while she was signing the delivery papers.
- Star Wars Legends: In the novelization of Revenge of the Sith, Palpatine (who is fully aware of Padmé's and Anakin's secret marriage) insinuates that Padmé is cheating on Anakin with Obi-Wan. When Anakin visits Padmé's residence to confirm these suspicions, he detects signs that Obi-Wan did visit her (to share his concerns about Anakin). While Padmé is able to assuage his temper, Anakin never really lets go of the insidious notion. Later on Mustafar, when Anakin sees that Obi-Wan stowed away on Padmé's ship, he takes it as a sign that Padmé has betrayed him. Cue Force-choking.
- In one of the Stephanie Plum books, Steph thinks Morelli's reviving an old affair with Terry Gilman. Turns out it's a business matter, and she nearly screws up a case the FBI has been working on for months when she confronts him.
- In a Sweet Valley High book, the twins and their older brother Steven become concerned about their father's apparently budding relationship with a coworker. It's never established if they were completely wrong or if there was something brewing before the father had the sense to end if before it could really get started. Earlier, in a Sweet Valley Twins book, the kids become convinced that their mother is having an affair with one of her clients and is planning to run off with him, even though there have actually been zero signs to that effect—they've simply taken everything nice that their mother says or does as romantic interest and when they take to spying on the man, they mistake his phone conversations with his girlfriend for lovey-dovey chats with their mother.
- Happened many times in the Teenage Worrier series:
- The Teenage Worrier's Guide to Life: Letty's mother disappears, but the family finds a note from "Neville" (the name of her ex-boyfriend) agreeing to pick her up. It turns out Neville is the husband of someone she was visiting to discuss a business venture, but she'd accidentally left his note to her on the table, rather than the note she had written for her family.
- In The Teenage Worrier's Worry Files, Letty meets a man named David who is a cross-dresser. She discovers letters between David and her father, describing plans to go on a trip together; and believes they are having an affair. David was actually helping him research for a new novel about a cross-dresser.
- In another book, Letty visits her friend Hazel's house to send her ex-boyfriend an email (since Letty doesn't have internet access at home.) His new girlfriend intercepts the message and writes a reply warning Letty to stay away from him, but Hazel's mother finds it and assumes her husband is having an affair. Hazel isn't happy with Letty.
- In The Teenage Worrier's Christmas Survival Guide, Letty asks to borrow a dress of her mother's to wear to a Christmas party, but the dress turns out not to belong to her mother, leading to an argument between her parents over whose it is (though it is suggested her dad isn't really cheating).
- Tortall Universe: In Trickster's Queen, Aly creates and plants fake evidence suggesting that Prince Regent Rubinyan is cheating on his wife Imajane with one of her ladies-in-waiting to drive a wedge between them for the rebellion's benefit. It results in both Imajane throwing a chair at her husband, and the lady in question being sent home covered in bruises.
- Paul Merton's sketch show had a sketch where his wife (played by Caroline Quentin, his real wife at the time) accused him of having an affair with Gloria Hunniford, because the same night he was out of town on business, she wasn't on TV.
- A standard Soap Opera trope (Ironic, considering the rampant affairs that DO happen):
- On General Hospital, Luke and Laura Spencer faked her death in order to flee from the evil Cassadines who had recently returned to Port Charles. Only two other people in town were privy to this—Luke's best friend Sonny Corinthos, and local psychiatrist Tom Hardy, who they needed to care for Laura's mentally ill mother. As Tom promptly became very secretive and withdrawn, his girlfriend Felicia began to suspect he was fooling around. To that end, her best friend Mac followed Tom as he went to visit the family, then burst in on them when he saw Tom hugging a woman, only to be stunned at seeing that the woman was the presumed-dead Laura.
- One Life to Live's ditzy Kelly arrives at the airport to pick up her cousin Cassie, only to see her with an attractive young man. Thanks to some Out-of-Context Eavesdropping, she leaps to conclusions and confronts the two, blasting them for their immoral behavior, only to end up looking like a complete idiot when Cassie informs her that the guy is her ex-husband's long-lost son.
- It can also be deliberately invoked if an outside party trying to invoke Relationship Sabotage:
- Port Charles's Courtney does this to Karen—planting a pair of panties in her boyfriend Joe's car, calling and hanging up—because she wants Joe for herself.
- Early in the first season of Alias, Francie suspects that her boyfriend, Charlie, is cheating. Sydney and Francie follow Charlie and find him meeting with an attractive blonde woman, into whose car he loads a bag, before driving off with her, while he has told Francie he has a law review. It turns out that she is his partner for a MUSICAL act, and he wants to be a singer.
- Invoked and played with a lot in 'Allo 'Allo!. Edith often catches René making out with one of his waitresses or some other woman, and each and every time he just comes up with a lame excuse to make her believe it's this trope. The kicker of course is that he is very much cheating on her. And she buys it every single time. He only drops the act in the final episode.
- In the Brazilian telenovela Anjo Mau ("Evil Angel") and its remakes, the father of the baby boy that the Gold Digger Villain Protagonist babysits is accused of cheating on his Clingy Jealous Girl wife since he periodically visits someone else's house and says nothing about his reasons to do so. The women he visits are actually his mother and sister.
- The Astronaut Wives Club: Amusingly, Gordo. He cheated in the past, but when his wife thinks he's enjoying the attentions of the Cape Cookies, she finds out he actually flirts with them, but anytime he's alone with one of them, starts gushing about how much he loves his wife.
- Used in an entirely non-comedic way in Battlestar Galactica. Cally spots her husband Galen having a long and intimate talk with Tory at a bar and accuses him of having an affair with her. He can't exactly tell her that he was really discussing that both he and Tory happen to be Cylons. And when Cally spies on them and discovers they are Cylons, Tory kills her. Galen kills Tory when he finds out. Also, Cally wasn't just imagining things because Tory and Galen were engaged in a past life and a bit of attraction was coming out in the bar.
- Just about every second episode of Bewitched revolved around Samantha mistaking Darrin for doing this, with Endora egging her on.
- Big Love does an interesting version of this as well. Husband Bill and his first wife Barb begin an "affair" (he is not supposed to sleep with her on nights designated for the other wives). Second wife Nikki notices his suspicious behavior, concludes that he is courting a fourth wife and is actually pleased, as she thinks it means she will gain a friend and an ally in her clashes with Barb and third wife Margene. When she discovers he's fooling around with Barb, she's hurt and disappointed.
- On Bones:
- A man with a history of infidelity is killed by his own daughter. His killer was furious that he'd apparently resumed fooling around again, unaware that the young woman he'd been meeting on the sly was his illegitimate child from a previous affair, and that their relationship was entirely platonic.
- During another case Booth and Bones see Sweets' girlfriend trying on a wedding dress and hugging a man. This leads them to assume that Sweets is the other man in this scenario. It turns out she was just the bridesmaid filling in for the bride since they had the same build.
- One victim was suspected of cheating by his wife's friend because she'd found an earring in his car and smelled tacky perfume on him that his wife wouldn't have worn. Turns out he was a Wholesome Crossdresser. The earring and perfume were his.
- Boy Meets World:
- One episode had the "kids think that one of their parents is cheating" version. They find out that their mom is sneaking off to have a romantic dinner with a mysterious man... who turns out to be their dad.
- Another episode had the parents checking into a hotel to celebrate the wife's pregnancy. At the check-in desk, the husband impulsively shares his news with a random woman, who gives him a congratulatory hug. Sure enough, someone sees this and leaps to the wrong conclusion.
- During the second season of Breaking Bad, Walter's wife Skyler doesn't buy his lame excuses to hide his secret activities. She assumes that he has an affair with their friend Gretchen Schwartz since he has private conversations with her (to ask her to keep the fact that she and her husband don't actually pay for his treatment against cancer), was missing for a couple of days and hide a second cellphone. She finds the truth much worse and immediately leaves him.
- Brothers and Sisters had the complication of Robert's presidential campaign. An investigator took suspicious photos of him entering a woman's home and showed them to a member of his staff, who happened to be his brother-in-law Kevin. Kevin is torn over his job and loyalty to his sister. In the end it turns out that the woman was actually his therapist.
- In Castle the Victim of the Week was killed over a girl in Cuba, leaving behind a very pissed off wife. Until she learns the girl in question was the victim's daughter. A double whammy followed, as the wife confronted the husband's best friend about the girl, who had no idea what was going on and was trying to calm her down and comfort her... when the husband walked in on them. Guess what conclusion the husband leapt to.
- Subverted in Cheers when Kelly finds Woody holding another woman (a pre-Friends Lisa Kudrow!) and immediately jumps to the right conclusion:
Kelly: Don't make excuses, Woody. Now I see what's going on. You're busy every night and you won't tell me why. I walk in here and find you two kissing in the back room of a bar. It all adds up. You're in a play and you didn't even tell me.
Woody: Wait, maybe I was just cheating on you!
- The title character begins dating his college sweetheart, Jill, who walks in on him and Sarah showering (they were trying to get a "poisonous" powder off of their bodies. It turned out to be Hi-C mix). He explains the situation and she is all-too-willing to believe him. This might have had some thing to do with the fact that Jill was evil and using Chuck.
- Additionally, after Bryce got Chuck kicked out of Stanford (to prevent him from being recruited for a dangerous mission), Chuck finds out that Bryce is also sleeping with Chuck's girlfriend Jill. Then it turns out that Jill made it up (on orders from her Fulcrum handler), and Bryce never bothered to set the story straight.
- Devon thought Ellie was cheating on him while she was being manipulated by an undercover Fulcrum agent.
- Alex may have thought this to Morgan blowing her off twice because of Carina.
- Cold Case
- In one episode, the wife of the victim had suspected her husband was having an affair with another woman who was also involved in a communist movement like him. She felt that she as a simple housewife couldn't compare to this exotic foreign woman. The woman in question would later reveal to Detective Rush that while she confessed her love for the husband, he remained faithful to his wife and family.
- In another episode, the detectives learn that a beautiful young black woman had visited the white murder victim at his office shortly before he was killed. His reaction toward her—looking very upset that she showed up, rushing her out of there—plus the revelation that he was sending money to her makes the detectives jump to the conclusion that she was his mistress. Only to have it turn out that she was his SISTER. He was passing for white and her appearance could have blown his cover.
- Subverted in "Forever Blue", where the detectives think that a murdered cop was having an affair with his partner's wife because a witness recalls overhearing a tearful argument between the two of them. When they confront the woman, she reveals that she wasn't having an affair with him—her husband was.
- Community: In the season 4 episode "Conventions of Space and Time", Jeff rented hotel rooms for himself and Annie under his name, causing the hotel staff to assume they were married, and Annie was all too happy to go with it. When Jeff is flirting with some random woman at the bar, the hotel staff informs Annie of this, who stomps down there and throws multiple drinks in his face, pretending to be jealous because she didn't want to admit anything to the nice hotel staff.
- CSI did this in "Genetic Disorder" with Doc Robbins' wife. Although Brass and Hodges refused to believe the couples' assertions they were faithful, it was proven to be a frame up made to look like she'd been cheating and a random one at that.
- CSI: Miami has this happen a few times.
- In "Game Over," a skateboard tester (Tony Hawk) is found beaten to death. The team zero in on his wife who snaps she was irate to find flowers to another woman delivered to their home and beat him with his own board. It turns out the flowers had been ordered by his boss for his girlfiend and sent to her address by mistake. Luckily for the woman, it turns out the blows weren't fatal and someone else actually finished her husband off.
- An episode has a man seemingly framed for murder and on the run with a young woman who also ends up dead. The first "murder" turns out to be faked as part of a huge live action role playing game the man's brother was playing to get him out of a funk. The man's wife found the "mistress" (who he never actually slept with) with her husband in bed and, getting the wrong idea, killed her.
- In CSI: NY Danny was suspected of this by Internal Affairs. One of his rookie cops shot an unarmed man while they were out for a drink-two guys attacked, and one did have a gun, but she shot the other one. Scared for her career, she told IA Danny told her to lie because they were having an affair, and IA was highly suspicious of a surveillance tape that showed her cozying up to Danny at the bar. Danny vehemently denied it, naturally, but Lindsay had to pressure her to tell the truth and admit what really happened.
- Also occurs rather more tragically to a Victim of the Week. Season 9, episode 16, a woman kills her husband because he began taking calls out of the room and locked his phone. She figured out the code, read his texts to a woman planning a vacation suspiciously similar to the wife's dream vacation, and assumed he was cheating. He wasn't, the woman he was texing was a travel agent, and he was going to take his wife on her dream vacation as a fifth wedding anniversary present.
- Daredevil (2015): A case of this happens in season 2 when Karen Page stops by Matt's apartment and sees a wounded Elektra recuperating in Matt's bed.
- The Indian sitcom Dekh Bhai Dekh has an episode where Suhasini suspects her husband Balraj of cheating with someone named Suzie after she hears him mentioning the name while talking in his sleep. "Suzie" is actually an Affectionate Nickname he gave Suhasini, but she enters the room after he mentions that part.
- Done at least twice on Dexter:
- In season 2, when Dexter and Rita were about to, er, do the deed, Dexters' NA sponsor calls... and mentions their road trip, where he confronted his mother's killer, and then they slept together (but did not have sex.) Unfortunately, he let the machine get it, meaning Rita heard everything... and thus, suspected he was cheating. Later on, Lila (the sponsor) and Dexter do have sex, but only after Rita says that their relationship is over. Which apparently she didn't mean, because you know how women can be... so irrational when they think their perfect man is sleeping with another woman. Dexter then confesses to having sex with Lila. Sort of. When Rita asks him to tell her if Dexter had sex with Lila that night, Dexter replies "No... Not that night."
- Played with in season 3. At first it's played straight when Miguel's wife suspects him of cheating... when, in fact, Miguel can't say where he was because he was committing a murder. Then later his wife catches when he did actually decide to rekindle an old romance, albeit for ulterior purposes. Dexter knew about it and was the one responsible for getting Miguel's wife to LaGuerta's.
- The Dick Van Dyke Show
- Rob thinks that his coworkers Buddy and Sally are having an affair, but it turns out they're just moonlighting as a comedy song-and-dance act.
- In another episode Jerry the best friend and next door neighbor is suspected of cheating on his wife when he's seen lunching in a restaurant with another woman. She turns out to be a marriage counselor.
- Doctor Who: In "The Shakespeare Code", Shakespeare's landlady, who it's indicated he's already having an affair with, has this reaction when she comes into his room to find Lilith there. Lilith is an alien witch who's using a Voodoo Doll to ensure Shakespeare writes the ending of Love's Labours Lost the way the witches want it. The landlady is subsequently killed due to her bad timing.
- In an episode of Drake & Josh, the eponymous characters think Walter is cheating on the mom. It turns out he was meeting with someone about a new job and wasn't sure about so he waited to tell his family. Drake and Josh screwed up his chances of getting the job, though.
- In the Hong Kong drama The Drive Of Life, one character saw her friend's husband having lunch with another woman and both were quite close to each other (such as the woman helping the husband try on a jacket). After the character leaves to tell her friend, we find out that the woman was an old friend of his and the jacket she helped him try on was for his son.
- On ER, Elizabeth discovers that husband Mark went to New York when she sees the charge for a plane ticket and hotel room on his credit card statement. Given their current estrangement and his Unresolved Sexual Tension with friend Susan Lewis, she naturally comes to the conclusion that they're having an affair. Only for the truth to be even worse—Mark went to New York to visit the neurosurgeon who had previously operated on him, because his lethal brain tumor has returned.
- In Eureka, Henry's cosmically retconned wife thinks his lack of intimacy is because he is seeing another woman. When she asks Jack about it, he says, "Oh, no, no, that's the least of your problems!" The real reason is because he's from a timeline where they were never married.
- Ever Decreasing Circles featured two instances of this for main couple Martin and Ann.
- In the Series 3 episode "One Night Stand", a practical joke-loving co-worker of Martin's arranges for him to find a strange woman in his bedroom one morning on a business trip. Martin is horrified to discover his "indiscretion" and immediately confesses to Ann, who becomes cold toward him until Paul tricks the joker into admitting the truth in front of her.
- In the Series 4 episode "Jumping to Conclusions", Hilda sees Ann climbing over the fence into Paul's garden for a study session for her Open University course. She concludes that Paul and Ann are having an affair, and word works its way back to Martin. Martin decides to leave Ann to what he sees as a happier life with Paul, but is set straight before he can make the separation permanent.
- In one episode of Everybody Hates Chris, Chris' mom believes her husband is cheating on her because he's become so courteous all of a sudden. The reason he was acting like was because he got hooked on The Oprah Winfrey Show and was just following the advise he heard on TV.
- A few episodes of Family Matters fit this trope. The first was "The Stake-Out" when Estelle and Rachel fear Carl is cheating on Harriet with his female police partner, Vanessa. They come into the stateout, and from what they see, they suspect that he was doing it. They realize they were wrong, and that it was a stakeout indeed. "Tender Kisses" involves Carl having Urkel reading diaries of Harriet, fearing she's cheating on him, only to find out that Harriet wrote a fake diary, to elicit a response from Carl, and to test his trust for Harriet.
- In the Fawlty Towers episode "The Wedding Party", Basil Fawlty twice catches his guest Mr. Lloyd hugging women who aren't Mrs. Lloyd. He tries rather awkwardly to keep Mrs. Lloyd from finding out. The two women are actually Mr. Lloyd's stepdaughter (Mrs. Lloyd's daughter) and a family friend of the Lloyds, and the hugs were perfectly innocuous.
- In the Flashpoint Season 3 finale, Jules and Sam decide to resume their Secret Relationship and start getting hot and heavy in his apartment, only for another woman to walk in. This briefly leads Jules to believe that Sam was cheating on another girl with her, but he later explains that the newcomer was actually his sister.
- In Foyle's War, this is done with someone other than the romantic partner. After Andrew Foyle dumps Sam via letter because he's dating someone at his new base, Sam accepts a date from a flirtatious American soldier, which causes her boss DI Foyle to become chilly towards her. She doesn't explain the situation until near the end of the episode (because Andrew's actions rather stung) but once she does, Foyle apologizes for making assumptions. When Andrew turns up again at the end of the series, Foyle shows him the same chilly disapproval when Andrew wants to ask Sam out again.
- Played with in Friends:
- Rachel and Phoebe see Chandler meet with an attractive blonde lady and follow them out to a house in Westchester where the two of them spend almost an hour together. They, Joey and Ross leap to the conclusion that Chandler is cheating on Monica when in reality the lady was a realtor who was showing the house. Kind of an Idiot Ball moment, since they immediately assume the worst about their friend. Inverts the conventional trope as Monica doesn't believe for a minute he's cheating and figures out who the woman actually is.
- Joey also mistakes Monica for cheating when he see's her hiding a guy in her apartment. ("I told you, you shouldn't have married someone so much hotter than you!") Again inverted as Chandler doesn't think Monica is cheating...because he's the one she's hiding.
- In the Get Some In! episode "Kit", Drill Sergeant Nasty Corporal Marsh buys a box of hankies from Teddy boy aircraftman Jakey Smith, who secretly has dozens of boxes he is selling at a huge profit. He sells another box to LAC Hodder, the quartermaster at RAF Skelton, who gives them to his girlfriend. When Marsh shows up with Aircraftman Second Class Richardson, who has lost his kit and needs a replacement, he finds one of the hankies and assumes it must belong to Alice, and he beats Hodder up in retaliation. However, when he discovers that Alice still has all the hankies in her box, he punishes Smith for being a spiv and Richardson for doubting Alice's fidelity.
- On Glee, the club's best dancers Brittany and Mike are tasked with coming up with a dance number for sectionals. All's fine and good until Mike's girlfriend Tina confides in Brittany's boyfriend Artie note that she suspects Mike and Brittany might be cheating on them with each other. When Artie asks Brittany if she wants to spend more time with him, she avoids the question, saying that she has to rehearse with Mike. Tensions run high all the way to right before the actual competition, and it turns out Brittany didn't want to talk to him because she lost the "magic comb" he'd given her as an encouragement token and wasn't really cheating on him.
- Later in the season, a blind item in the school newspaper implies that Quinn is cheating on her current boyfriend Finn with her ex-boyfriend Sam note , sending Rachel and Finn on a stakeout of the motel where they are supposedly hooking up. While spying on the motel they spot both Kurt and Quinn leaving Sam's motel room, and come to the conclusion that both of them are cheating on their boyfriends with Sam. Turns out that Sam's family lost their home after his father lost his job, and all of them - mother, father, three children - are living in that one hotel room; Quinn was helping Sam babysit his younger siblings and Kurt was helping out by giving Sam some second-hand clothes.
- In The Good Fight, Diane suspects that her husband is cheating on her; when she finds a blonde Affair Hair in his clothes, she is convinced and confronts him about it. It turns out that he is cheating on her... with Eric and Donald Trump Jr. She doesn't seem to be sure if the misunderstanding is funny or if it's actually worse.
- Happens on The Good Life when Tom and Barbara discover that Margo has not been taking riding lessons like she claimed. They try desperately to keep the secret from Jerry. It turns out she has actually secretly been going to weight loss classes.
- In one episode of Goodnight Sweetheart, Gary becomes convinced his 1940s wife is having an affair with his next door neighbour ... who happens to be Noël Coward.
- James Wilson on House gets accused of this by House every time he so much looks at a woman (to be fair, he did cheat on two of his wives and told them about it later). This trope is actually the entire B-plot of "Fools for Love", in which it's subverted — it's not Wilson that Nurse Wendy is dating, it's Foreman.
- In another episode, House and Stacy, his ex, are washing dishes at her place when her husband comes in. House (acting surprised): "It looks like we're washing dishes, but we're totally having sex."
- There's an episode where a married couple is found to have genital herpes. The wife, naturally, is furious, assuming her husband to be unfaithful. He denies it. House then proposes that one of them could've picked it up in a public toilet. The wife claims she knows about it and always covers the toilet seat. The husband claims he never knew. All seems resolved... then House points out that the husband agreed way too quickly. Turns out the guy really is a cheater who was just trying to avoid the reveal by accusing his wife of being a cheater (not sure what his "best case" scenario was there, that she would reveal it was true?)
- House of Anubis:
- Eddie begins to believe towards the end of season 2 that Patricia is seeing someone else because of how often she disappears without telling him why, and he suspects it might be Alfie. He eventually follows her, Fabian and Alfie when they leave for the barn and finds out the truth.
- Patricia later believes Eddie himself was cheating on her season 3. In the beginning, she and Fabian believe that Eddie and Nina had a summer romance and that's why Nina didn't come back, because of some emails they found on Eddie's computer and the fact that he had Nina's locket. It turned out that Nina gave him the locket because he might need it, and the emails were about the whole Chosen One and Osirian thing. Later on, Miss Denby tricks Patricia into believing Eddie is cheating on her by placing fake messages on his laptop and manipulating her into reading them. It doesn't get resolved too easily, as Patricia turns into a sinner for getting upset over this, which was the whole plan. Both times, this was Played for Drama rather than laughs.
- How I Met Your Mother:
- Robin has mistaken two of her boyfriends for cheating: Ted in season two (she had heard second-hand stories of Barney claiming to be Ted) and Barney in season five (who was actually sneaking around to learn more about Robin so he could be a better boyfriend to her).
- Also with Ted's parents with a slight twist. Barney takes a picture of Ted's father making out with a girl, leading Ted to furiously confronting his father. However, it turned out that his parents had been divorced for almost ten months and separated for two years, intentionally not telling their son because they feared the news would crush him.
- It's also revealed that Lily has invoked this a few times when she has disapproved of woman that Ted has been in a relationship with by leaving around an earring for the women to find.
- In the TV show The Invisible Man, there's one episode where the main characters find a man who faked his death by showing his girlfriend a picture of one of the Agency's scientists, an attractive blonde, and claiming the man was having an affair with her. They also plant other signs—lipstick and perfume on one of his shirts, etc. The girlfriend storms off to confront the supposed cheater, leading the main characters right to his hiding place.
- In Jeeves and Wooster, this happens to Gussie Fink-Nottle all the time, primarily in the first episode of season 2. This is especially bad, because if Madeline broke off her engagement to him, then Bertie would have to marry her. Either that or explain that he would rather die, which would be bad manners.
- The Jeffersons has multiple examples:
- In one episode, the "other woman" turns out to be an old war buddy of George who recently underwent a sex change.
- Louise finds out George has been giving money and presents to the people in a certain apartment every Christmas, and wonders if he's having an affair or secret children she doesn't know about. It turns out he's just been anonymously helping the family who lives in his old apartment, since he remembers how hard his family had it when he was a kid.
- Louise has told George she doesn't want him to work late anymore. George sneaks in from working late and is fact building another store. When caught by Louise, he lets her think that he's having an affair rather than working so much.
- Louise catches George in a hotel room with another woman. It's a long story, but it's completely innocent. However, when he tells her that there's nothing going on between him and the woman, she believes him instantly because she notices that he doesn't display the physical tic that usually tips her off to when he's lying.
- The central focus of the first Kamen Rider Double Returns mini-film is that Ryu Terui/Kamen Rider Accel is framed for murder... and supposedly has run off with a mysterious woman, which infuriates his new wife Akiko and has her running to file divorce papers. (In reality, she's a pickpocket he was in the process of arresting when everything went to hell; they're handcuffed together and he lost the keys.) Not at all helping is the fact that another character is playing with Akiko's worries for a laugh and because she herself has a crush on Ryu; she's the one who gives Akiko the divorce papers, earning a What the Hell, Hero? from her grandfather.
- A strange variant happens on The King of Queens. Carrie is upset that Doug loves Spence's girlfriend Becky's cooking, since Carrie herself is a mediocre cook. She gets so upset that she bans Doug from eating Becky's cooking or even going to her house. When Carrie confides in her father Arthur about it, he assumes that "eating Becky's cooking" is a euphemism for "cheating". Later on, when Doug gets angry at Deacon for eating Becky's food, Deacon asks if they were sleeping together.
- Done this way and that on all versions of Law & Order. One noteworthy example has the detectives confronting the husband about his clandestine behavior only to have it turn out that the "other woman" was his WIFE and that the sneaking around was an attempt to put the spice back into their marriage. Another had the SVU detectives confronting a man they assumed to be a dead woman's lover, only to have it turn out he was her husband's boyfriend (it's a long story, but suffice it to say, everyone was aware of what was going on, and no one was guilty of murder).
- On Modern Family, Claire has always wondered whether her father Jay ever had an affair, considering his frequent business trips and his rough, soon-to-be-failed marriage. When she goes with Jay to a trade convention, Jay acts suspiciously close to one of his female colleagues, and a conversation Claire overhears only confirms her suspicions. (Turns out they're not talking about any affair, but the time they conspired to get rid of Claire's then-boyfriend Phil by offering him a high-paying out-of-state job.)
- In another episode, Jay comes home from a business trip early and opts to stay in a hotel while claiming he's still away on business. He's just trying to get some decent sleep (his pregnant wife is snoring a lot) but when she finds out, she naturally assumes an affair.
- On Monk, Captain Stottlemeyer asks Monk and Natalie to follow his wife, whom he suspects is cheating. They take pictures of her out with another man, and Stottlemeyer confronts her. The good news: she's not cheating. The bad news: the man is a divorce lawyer.
- Another episode, "Mr. Monk and the Bully", has Monk and Natalie follow another client's suspected cheating spouse - he suspects it based on her clothing. They follow the spouse, and catch her in a bar with someone else. The next day, he turns up dead. In the end, it turns out that the spouse was not cheating, and Monk and Natalie were following her identical twin sister.
- Motive: In "The Dead Name", a blackmailer thinks that the wife of a famous footballer is having an affair and threatens to expose her secret if not paid off. However, the wife's secret is actually that she is really a trans-woman, and she has been meeting up with her ex-wife. However, because the blackmailer never specifies what the secret is, she believes he knows something that would be far more scandalous. This confusion results in the murder of both the wife and the blackmailer.
- On My Name Is Earl, in his coma dream, Earl eavesdrops on Billie's phone conversation with Joy, and comes to the conclusion that she's been hiring a gigolo while Earl is at work. Earl hides out in the living room to catch the gigolo...only to find out that the person Billie was referring to was an obstetrician.
- On My Own Worst Enemy, Tom's wife begins to suspect that he's cheating on her when she finds out he was lying about being on a business trip. In fact, Tom's other personality, Raymond, was off on a spy mission, but since Tom doesn't know this, Raymond's bosses have to alter his memories to make him believe he really was cheating. They were actually sort of rekindling their relationship... then she witnesses Raymond (she thinks it's Tom) shooting someone at night.
- The Nanny: In "Schlepped Away", Fran mistakenly thinks that her mother Sylvia is cheating with the butcher when she finds a love letter stashed in a packet of meat. It turns that Sylvia just flirts for lower prices, with Fran's father Morty's blessing, no less.
- On Nashville Teddy Conrad is running for mayor of Nashville and is photographed comforting a woman who is not his wife. He is not cheating but he can hardly explain to the voters that he was comforting the woman because she was his accomplice in a fraud he once committed and she was scared that they would be exposed. In turn Teddy's wife is often suspected of cheating on him because she is still very close to Deacon Claybourne who was her boyfriend before she met and married Teddy.
- In Noah's Arc, Alex suspects Trey may be cheating with his friend Guy. Early on he investigates it and finds he was completely off base. A subversion comes up though in that later we learn Guy was secretly pursuing Trey all along, without Trey's knowledge.
- Northern Rescue The first season finale has main character Scout having some Ship Tease with his sisters friend Gwen, only to walk in on her and his Bully Turned Buddy Jason, whose changing shirts (because someone had just spilled a drink on his), leading him to angrily attack Jason, damaging his relationships with both of them.
- In the Only Fools and Horses episode "The Jolly Boys' Outing", both the Trotter brothers fall into this trope. During their weekend in Margate, they meet up with Del's then on-again off-again (and future wife) Raquel, who is currently working as a Lovely Assistant to a Stage Magician called the Great Raymondo. When Del discovers Raquel and Raymondo share a flat he flies of the handle and punches Raymondo before the man can explain he's gay. On their arrival home, Rodney discovers Cassandra's boss is visiting the flat and they've been looking at holiday brochures (Del had previously fanned the flames of jealousy so Rodders would agree to go out for a drink) and likewise starts an altercation. It turns out the guy's wife was also visiting, and they were discussing places Cassie and Rodney could go together. While it's intially Played for Laughs, it turns out to be Played for Drama in subsequent episodes, as it takes a lot of time for Rodney and Cassandra's relationship to recover. In the episode "The Chance of a Lunchtime", just as things seemed to be getting back on track, Cassandra thought Rodney was cheating when she saw him leave the Nag's Head with Del's ex. (just to get her a cab).
- Parks and Recreation: Ann thinks Chris is cheating on her because he's so distant, so Leslie investigates. It turns out he's not cheating. He's distant because he dumped her a week earlier, but he was so friendly and upbeat (and Ann had never been dumped before) that she didn't realize what had happened.
- In one episode of The Pretender, Jarod encounters a runaway kid named Dylan whose mom is working in England and whose dad (Peter) is a workaholic lawyer who seemingly dies in an explosion. The folks split up because the mom overheard Peter talking on the phone to someone named Ashley and thought the worst. Jarod's investigation into all this reveals that Peter wasn't having an affair; he was informing to FBI Agent Matthew Ashley about the firm's illegal activities (including silencing witnesses). Peter chose to let his wife think it was an affair so that she'd be away from the firm's goons as things went down, but then Ashley was killed by way of Make It Look Like an Accident and the evidence was stolen. After Dylan didn't show up for school that day, Peter panicked and faked his death to buy more time to figure out his next move. Luckily, Jarod manages to expose the firm's activities and reunite the family.
- Done on Psych, but not as a major plot point. Shawn's date confesses that she has a boyfriend, but plans to dump him because he's cheating on her. When she lists the evidence, Shawn realizes that her boyfriend isn't cheating; he's actually planning to pop the question.
- Raising Dion: When Nicole discovers that her late husband Mark had secretly been in contact with a woman named Charlotte Tuck, she at first fears the two had an affair. When Charlotte first meets Nicole, she quickly dismisses this accusation. The real reason they had contact is because they both got superpowers from exposure to an Aurora Borealis in Iceland; something Mark had kept hidden from Nicole.
- Ray Donovan: Double Subverted: Abbey knows about Ray's repeated affairs, and it strains their marriage. When Ashley visits Ray's apartment, and handcuffs herself in his bathroom, demanding they have sex, Ray just leaves her, and has his secretary, Lena, come in later to cut the cuffs and send her home. Ashley spends the entire day bored, and after she cuts her leg she tries to write a message on the mirror in blood... only for the wound to close after she writes only 2 letters. After Lena cuts her out, Abbey stumbles into the apartment, sees the broken handcuff, and blood on the mirror, and instead assumes Ray's been torturing people, before falling back on her old assumptions and (correctly) guessing that he was having another affair.
- Rumpole of the Bailey:
- Mrs. Rumpole (Hilda, a/k/a "She Who Must Be Obeyed") thinks her husband's cheating on her. Actually, He's taking dance lessons because she's mentioned being annoyed that he can't dance with her in the past. At the end, it's a CMOH when they dance together.
- In "Rumpole and the Married Lady" a series of partially overheard phonecalls by Hilda, listening in to Rumpole having to deal with a somewhat overwrought and needy female client during a bitter divorce, leads her to think that Rumpole may be cheating on her. Hilda even briefly moves out to visit a friend, but thankfully realises that for all his faults that Rumpole is not the cheating sort.
- In Seinfeld, this happens to one of Jerry's Girls of the Week when George claims to have seen her making out with Jerry's cousin Jeffery. Even though he had lost his glasses, he still claims he could see perfectly since he was squinting. This claim is backed up when he spots a dime on the floor all the way on the other side of the room, and by Jerry himself when he recounts a time when George lost his glasses while driving and squinted his way to their destination, spotting every obstacle along the way. At the end of the episode, George sees the two of them making out again, only this time he has a new pair of glasses, which he puts on only to see... an old woman affectionately petting her horse (Jeffery was said earlier in the episode to have a horse-like appearance).
- In Smallville, it once happened with Lana's biological father's wife. She follows Lana and insists that it's not what it looked like: the other man she was talking to was not a love interest...however, he was a divorce attorney. Ouch (they do end up salvaging their marriage though).
- Soap: Burt walks in on Mary and her English professor having a snog on the couch and assumes they're having an affair (which is what he was afraid might happen if she went back to school). But it's really her professor throwing himself at her. Right after Burt leaves she slugs the prof and throws him out of the house.
- A drunk Burt then goes to his secretary Sally's apartment. Sally had been throwing herself at Burt. He sleeps off his drunkenness but Sally makes him think that he had sex with her, so now Burt mistakes his own behavior for cheating.
- Played with in Spaced: Marsha, who believes Tim and Daisy to be dating (when they aren't, but merely pretend to be to rent her flat), believes Tim to be 'cheating' after seeing Tim kissing his girlfriend Sophie. This leads to a confrontation where Marsha threatens to reveal the 'truth' to Daisy; however, Tim - unaware that she has seen him, and believing that Marsha is actually talking about a birthday cake Tim has arranged as a surprise for Daisy, completely misinterprets Marsha ("But... you'll spoil the surprise."). Chaos, not unnaturally, ensues.
- Happens in a Tales from the Crypt episode. A jealous and insecure husband overhears his wife planning something with his best friend. As he overhears more of the planning, he becomes more and more suspicious. He ends up killing both and, dragging her body behind him, stumbles into a surprise party planned, where she was going to tell him she was pregnant with their long-awaited child.
- In the Tales from the Darkside episode "Florence Bravo", a woman eavesdrops on her husband and spots him talking to an attractive woman. As soon as she leaves in anger, it is revealed that the woman is simply a lawyer who was helping the husband with their new house. Unfortunately, a few minutes after the lawyer leaves, the wife returns and shoots her husband, oblivious to the truth.
- In That '70s Show, Donna finds a pair of panties in Eric's car. She logically gets angry and believes Eric is cheating on her with a girl named Shelley. The panties belong to Donna's mother Midge... since she and Bob had some "fun" in there.
- In The Twilight Zone (1985) revival, "Love is Blind", this is part of the big twist: it turns out the protagonist's wife isn't seeing another man, she's meeting with an old friend to try and decide what to get for the protagonist's birthday. If the stranger of the story hadn't intervened, the protagonist would have shot her.
- In UFO, a flashback to the founding of SHADO has Straker in secret meetings with his new staff. His wife grows suspicious about his late night meetings and discovers him meeting with a female crewmember and makes makes the wrong assumption. Because of the secret nature of SHADO, he can't tell his wife what's going on so she leaves him.
- In "Shadows in the Sky", the Victim of the Week had been having clandestine meetings with a young woman. His son had discovered this and assumed his father was having an affair. The police consider this as a possible motive as the wife or the son might have murdered him for his infidelity. However, the young woman was actually his daughter from a one-night stand decades before.
- In "Protected", a husband suspects his wife is having an affair when he discovers his wife has a pay-as-you-go mobile phone, and has been lying about working late at the dog shelter. He eventually steals the phone and uses it to lure the younger man she has been meeting into an ambush, where he murders him. He later discovers that the man was not his wife's lover, but her son, who had been raised as her brother following a Family Relationship Switcheroo.
- In the Warehouse 13 episode "Where and When", it turns out the guy they think has this week's Artifact is meeting his secretary to plan a takeover of the magazine they work for. Too bad he never let his wife in on the plan. Part of it has to do with how the guy treats women. Everybody assumes him to be a mysogynistic Jerkass. It turns out that's just a cover he's putting on for the magazine big shots. He actually thinks very highly of capable women and has no problem with them holding his positions in the company. His attitude is actually pretty ahead of its time (the episode's set in the 1960s.)
- In The West Wing, season 7: Bruno and Vinick find out that Santos discreetly gives a certain amount of money every month to a woman whom he had hired while he was the mayor of Houston, and that the woman has a seven-year old daughter. Bruno and Vinick debate letting the public know about this. Vinick eventually confronts Santos about this; it turns out that Santos's presumed daughter is actually his niece and that he didn't cheat on his wife.
- The Without a Trace episode "Midnight Sun" had a supposedly loving family man disappear, only for witnesses to report seeing him on several occasions at a diner in the company of an attractive young woman. A trace on the woman's credit card reveals that she is in fact a deputy U.S. Marshal, and the man's handler in Witness Protection.
- From the Wizards of Waverly Place episode "Future Harper":
Harper: I had my mom's private investigator track her down.
Alex: Oh, how's the case going?
Harper: Oh, everything's fine. Turns out my dad was just sleeping in the car.
- The Mecano song "Hijo de la Luna", covered by Sarah Brightman. A gypsy woman makes a deal with the moon to find her a husband, as long as she agrees to give up her first-born child in return. The baby ends up as pale as the moon. Her husband ends up killing her, and the moon gets its child.
- Played darkly in mothy's Vocaloid song in the Evillious Chronicles, "The Tailor Shop on Ebizaka" where the tailor was upset that her lover hasn't been coming home to her and finds out he was seeing three different girls on different occasions. She kills the three girls and took their clothing/accessories thinking it would make her beautiful to her lover. It turns out that her "lover" doesn't even know who she is and the three girls were his wife and two daughters. She then kills him too, offended by his lack of recognition.
- "Happy" by Mitski covers this. It features a protagonist watching her happy marriage fall apart after her husband returns home from war. She becomes increasingly suspicious of the jewellery he gives her, and where he goes late at night. Despite having dark hair and eyes, she finds a lock of blonde hair and 'For My Blue-Eyed Cookie' embroidered on a bag he gave her. It is all but confirmed that he is having an affair, as we see various shots of him seducing different women. And then she goes down to the basement... To find him hacking a female corpse with an axe and removing her jewellery to clean. The shots of him seducing women now show him smothering them with chloroform. Unfortunately, he spots the wife as she trips trying to running away and starts to choke her. Fortunately, she manages to grab the axe and (presumably) kill him. We then see shots of her driving away.
- Implied in the Christmas song "I Saw Mommy Kissing Santa Claus." Because "Santa" is presumably the child's father wearing a costume.
- In the Biblical account of the Nativity of Jesus, Joseph initially assumed that Mary's virgin pregnancy was the result of infidelity, until an angel explained the truth to him.
- One Jewish legend says that David was conceived due to a Bed Trick after his father, Jesse, stopped sleeping with his wife; as a result, Jesse assumed David was the product of an affair throughout his childhood.
- In the Ramayana, Sita is held hostage for a year in Ravana's palace, during which time she turns down all of his advances, because she is Happily Married to Rama. When she finally gets out, Rama assumes that she slept with Ravana and wants no more to do with her. Sita agrees to undergo a Fidelity Test involving walking over flames, and passes the test with flying colors. In some versions, this appeases Rama, but in others, it's still not enough to convince him.
- In Hawaiian mythology, Pele saw her sister embracing one of Pele's lovers. The pair had bonded over the course of a journey they undertook on Pele's behalf, and the embrace was platonic. However Pele assumed they were having an affair, and drowned them in lava, which killed her lover. In a dose of pure irony, once Pele's lover was resurrected by Pele's sister, he actually did chose to be with the sister rather than Pele and the two became lovers for real.
- Happens twice in The Space Gypsy Adventures (oddly enough, both episodes were written by Space Gypsy guest contributor David Monid):
- The first time, in Damien's Valentine's Day Panic, is covered in Relative Error, but in short, Jehlise accuses Damien of dumping her in favour of 'one of his own kind'(the other girl is a fox cub with raccoon markings, like Damien). Luckily for her (and arguably for Damien as well), it turns out that it was actually a supposed cousin of Damien.
- It next happens in The St. Valentine's Day Mix-Up. When Gemma discovers that a Valentine's card from Duke has Fluff Catt's name inside it, she goes absolutely berserk at him, and throws him into the Spaceport duck pond. She finds out later that the card for Fluff was actually from DC Bones, who had asked Rekki to pass it on to Fluff, but had forgotten to sign it with his own name.
- Some of the villains of Ravenloft have this trope in their backstory. Anton Misroi caught his wife in the arms of another man, whose shoulder she'd been crying on because Anton was so cruel. Romir Hiregaard leapt to conclusions after seeing his wife and a family friend arm in arm, unwilling to believe that he'd interrupted a waltz lesson. In each case, the wives wound up murdered, and the villains, cursed by the Dark Powers.
- William Shakespeare used this plot device:
- It's played extremely seriously in Othello, when the title character believes that he overhears his friend Cassio laughing about sleeping with Othello's wife. Cassio is in fact talking about another woman entirely, and the whole thing had been set up by the villain of the piece in order to mess with Othello's head, but nobody discovers this in time to prevent the usual Shakespearean tragedy ensuing.
- See also- The Merry Wives of Windsor, Much Ado About Nothing, Cymbeline, and The Winter's Tale.
- This happens to Fiyero and Elphaba in act 2 of Wicked. Somewhat subverted in that Fiyero most definitely did want to be cheating on Glinda at the time.
- Lord Windermere in Lady Windermere's Fan. The woman his wife suspects him of is actually blackmailing him with a secret he wishes to protect his wife from. She redeems herself later on, though.
- In The Cat and the Fiddle, Victor spends most of the second act under the mistaken impression, furthered by Odette, that she has been sleeping with Daudet.
- The Children's Hour revolves around this. A little girl accuses her two female teachers of having an affair in order to avoid going to school. It ruins their social lives, ruins their teaching careers, and Karen's fiance leaves her due to doubts. The 1933 film adaptation These Three changed it into accusations Joe was cheating with Martha, though the 1960 remake keeps the original plot.
- An urban legend which dates back to at least the 1970s involves a man finding a strange car in his driveway, assuming it belongs to his wife's lover, and pouring cement into it — only to realize too late that the car was a gift from his wife and that what he assumed was her lover was actually the car salesman. In other variations, the wife is cheating, but the lover leaves the house with a different vehicle from the freshly-cemented one. Don Tyson, late CEO of Tyson Foods Inc., was involved in a version of the tale where his wife spotted his car in another woman's driveway and called a cement company to dump cement in his car, which was dismissed as apocryphal by the company.
- Amnesia: Later pulls this in Ukyo's After Story. The heroine finds notes that make it appear like Ukyo is living with another person, assuming it's a woman, and she worries that this is why Ukyo was so against the two of them spending time together in the evening or was hesitant to invite her over to his place. When Ukyo learns of her worry, he explains that he has a split personality, the notes are a way for the two of them to communicate, and that his split personality is more likely to appear when Ukyo is tired, hence keeping himself away from her when it gets to nighttime.
- In Bioshock Infinite this befalls the Big Bad and Dark Messiah Father Comstock. Over-exposing himself to machinery that let him see the future have rendered him sterile, meaning he stole "his" daughter from an alternate-reality version of himself who never became Father Comstock. He told his wife it was a miracle child that God had made from whole-cloth, which she understandably finds hard to believe and accused Rosalind Lutece of sleeping with him. Rosalind responds by telling her what really happened, which she finds even harder to believe, eventually leading Comstock to murder her to keep her from spreading doubt.
- Invoked and played for laughs at the beginning of Duel Savior Destiny. Taiga is currently attempting to get a hundred girlfriends at once and calls one of them by the wrong name, at which point he attempts to play it as a joke with this trope. She doesn't buy it.
- In The Elder Scrolls V: Skyrim, Ranmir thinks that his fiance Isabelle "ran off with a thief named Vex", assuming that Vex is male and that Isabelle was cheating on him. Turns out that Vex is actually a woman, Isabelle's old friend, and that she had gone to Vex to ask if she knew of any treasure; Isabelle wanted to fix Ranmir's financial problems and make him happy. She had died in the attempt. The player gets to show Ranmir a note she had written before her death explaining everything.
- In Fantasy Life, part of the prologue for novice Miners involves helping out Master Duglas, who hugged a strange woman in a case of Mistaken Identity and, in the process, lost his anniversary gift for his wife Ruby.
- Fire Emblem Awakening.
- Sorta. When Chrom shares a hug with his Kid from the Future Lucina before they explain their relationship, they get caught... by Lucina's mother, who has no idea of what's going on, and ends up wondering if they're having an affair (The exact reactions are different per girl). They explain the situation, Lucina hugs her still shell-shocked mother, and everything will be solved.
- If Chrom and a female Avatar DON'T get married, the Avatar's supports with Lucina will involve the latter accusing the first of either being Chrom's lover or intending to seduce him.
- In Galaxy Angel Moonlit Lovers, Ranpha suspects Tact of cheating on her with Chitose because she walked in on their hands touching while picking up papers. He spends much of the rest of the story path trying to win her back, eventually dressing up in a ridiculous pink "I love Ranpha" outfit.
- The Wolf Among Us: Beast is concerned by Beauty's disappearances late at night and is worried that she may be trying to hide a dark secret. When he finds her with Bigby at a seedy motel, he assumes the worst and a scrap breaks out. The truth is that Beauty has been secretly working at the front desk to help pay the rent, and Bigby is there to investigate a murder.
- Exaggerated in Phoenix Wright: Ace Attorney - Trials and Tribulations. Pearl beats up Phoenix several times for his supposed cheating on Maya, even for such innocent actions like talking to another woman or looking at another woman. Made more ridiculous by the fact that Maya isn't even Phoenix's girlfriend.
- Fate/Grand Order: When Altera and Brynhild meet for the first time, Brynhild sniffs her and smells her lover Sigurd's scent. She concludes Altera must have slept with him and angrily attacks her. Altera and Mash realize that Brynhild smelled Siegfried's scent on Altera and mistook it for Sigurd's, since the two men come from similar myths. And the reason why Altera has Siegfried's scent is because she had married Siegfried's wife Kriemhild. They try to explain this to Brynhild, but she won't listen, so they are forced to beat her into submission.
- A Hat in Time: Queen Vanessa, already an unhinged Clingy Jealous Girl who seethed when her prince studied law abroad under a female professor, and tried to ban bacon from the house because she was afraid he loved it more than her, had her paranoia vindicated when she caught him holding hands with another woman. The woman was actually a flower seller and the prince was merely handing her money because he was buying some flowers for Vanessa. Unfortunately, the sight had caused Vanessa to completely snap and chain her prince in the basement to make good and sure he would never leave her, where he remained until he transformed into The Snatcher.
- In Peter Is the Wolf, Peter gets knocked out and kidnapped by a long time stalker of his. As she is about to rape him, his girl friend bursts in, mistakes the rape attempt for him cheating on her, dumps him on the spot and runs off.
- A variation occurs in Fox Tails, when the Raised by Wolves (or rather, foxes) amnesiac girl Miyo tells Keen Kotoru's childhood-friend-with-a-crush, Crystal, that she 'slept with him'. She did, indeed, sleep in his bed... while shapeshifted into a fox. The fact that Miyo habitually refers to Keen as 'Master' probably doesn't improve Crystal's view of her either.
- In Skins, Jordan walks in on what seems to be Vinnie making out with another woman. It later turned out the other woman spontaneously kissed him and only because she thought he was dead and was delighted to see him alive but Jordan was so mad she bashed Vinnie over the head with a whiskey bottle.
- The Order of the Stick
- Subverted here, where Nale thinks Sabine is angry with him for making out with Haley (as part of a plan to kill her), until Sabine tells him she's actually angry about the fact that he was going to kill Haley without her. She then points out that she's a succubus, literally an incarnation of illicit sex, and being faithful to one's lover is not exactly high on her priority list.
- Defied here, where Elan mentions the common story progression of him staying silent about what happened with Therkla, Haley finding out scattered hints about it and misinterpreting them, and romantic tension arising because of that... and then says "to hell with all that" and says that he feels that he needs to be fully honest with Haley if he ever expects a happy ending, even if it gets in the way of some good narrative conflict.
- Subverted in College Roomies from Hell!!!, where Marsha walks in on her boyfriend Mike spanking the monkey - which is to say that literally, he has a pet monkey which he is punishing for having messed up the apartment.
- Punch an' Pie has this happen constantly to Heather at the beginning of the strip. Her girlfriend Angela seems to think that literally every single one of Heather's friends is a possible affair. Since Angela believes that Polyamory is natural and both women are bisexual, Angela is very jumpy about Heather having any contact with anyone outside their relationship. Heather breaks up with her over it.
- Used as part of a revenge plot in this Penny Arcade.
- Almost happened in the Walkyverse, but was averted. Danny is talking with ex-girlfriend Sal and mentions that he is planning to ask current girlfriend Billie to marry him.
Sal: Can I see the ring?
Danny: Hell no. I know how that works. I show you the ring, and Billie walks around the corner.
- In Kevin & Kell, when Bruno starts taking classes with fellow herbivores, he meets a rhinoceros named Rachel Einhorn. She is attracted to him at first sight, angering Corrie when she gives him a kiss after saving him from some coyotes and thinking he is cheating on her. It turns out that she, a lesbian, thought he (a "trans-diet" wolf wearing a sheepskin) was a sheep, resulting in him wearing ram horns with his sheepskin from that point on.
- In General Protection Fault, Craig is thought to be cheating on his wife with Sharon, as Nick and Dexter spy on the two. Similarly, the German, while taking on Craig's identiy during his business trip to Paris with Sharon, makes advaces on Sharon, but when she rebuffs him, realizes that he has misunderstood their relationship.
- League of Super Redundant Heroes has a gem. The worst part of it, even through the husband walks home to find his wife in dominatrix gear being tied up by a guy dressed like a gimp, it IS indeed not what it looks like.
- In Commander Kitty, MOUSE lets a depressed Ace listen in on a conversation between Freeda and Mittens, cutting off just as Freeda declares her love...for nectarines. Ace is not amused.
- The aftermath of such occurs in this short comic, where the boyfriend explains that the other girl he gave a kiss to was just his sister. Then it turns out to be incest. And he had sex with her just after the kiss. And offers to let his girlfriend join and make it a threesome.
- In Questionable Content, Dora finds Marten and Faye on the couch in their bedclothes hugging and jumps to the entirely wrong conclusion. The setup starts here.
- In the SuperMarioLogan episode, "Jeffy's Cellphone!", Jeffy calls a prostitute, telling her his name is Mario, and asking her to touch his "pee-pee" for five dollars. The prostitute shows up at the end of the video and tells Mario they talked on the phone. Mario is confused, and Rosalina thinks he's cheating on her. After the prostitute tells Mario she's going to touch his "pee-pee" for five dollars, an angry Rosalina beats Mario up.
- A variant in this Not Always Right story. A male checking into a hotel assumes the female desk clerk is writing some sort of proposition on his keycard folder and assures her that he has no intention of cheating on his wife.
Clerk: Sir, this is the password for the Wi-Fi.
- Dexter's Laboratory: While listening behind a door, Dexter and Dee Dee suspect their parents. It turns out they were playing Scrabble.
Mom: Hey, are you cheating?
Mom: Then what's this letter I found hidden in your pocket? Well!? Explain yourself this time!
Mom: I don't believe you! Passion? Passion!? Is is what that letter was all about? Just so you can have passion!?
Dad: Well how about the last time I caught YOU cheating?
Dad: Hey, what are trying to do? Kill me with that thing!?
- The Amazing World of Gumball:
- In "The Plan," Gumball, Anais, and Darwin discover an apparent love letter from "Daniel Lennard" to Nicole reading "Your beauty and happiness is important to me," spend most of the rest of the episode drawing up an elaborate plan to stop "him," and find out only in the end that "he" is just a cosmetic brand. Notably, the children think that Daniel Lennard wants Nicole to be his mom, and the issue of Nicole's fidelity to Richard is never brought up.
- In "The Lady", Darwin and Gumball come home early to find a middle-aged woman leaving their house, and come to believe she's Richard's mistress after witnessing him apparently making love to her. In truth, said "woman" is Richard Disguised in Drag to hang out with a group of old ladies. Unlike in "The Plan", the brothers very explicitly think it's a romantic affair, getting incredibly upset while confronting their father about it—though Richard thinks they just found out about his other persona.
Richard: Is it so bad that I have some fun? I enjoy the time I spend with my girls.
Gumball: Girls!? Plural!?
Richard: What difference does it make if it's more than one?
Gumball: You maggot. How many?
Richard: Three at the moment, but you know, the more the merrier.
- The Boondocks episode "Tom, Sarah and Usher" is about Tom becoming jealous of Usher when his wife Sarah starts obsessing with him. Their daughter Jazmine even worries if they will divorce, though Tom insists that won't happen. It later turns out that Sarah was just a fangirl, and never intended to cheat.
- The Crumpets: In "Family Secrets", T-Bone the dog brings a dug musicbox containing a letter to Ditzy Crumpet, who is shocked from reading the letter and interpreting it as proof of her father being in an affair. Following an emotional breakdown due to her family not helping her grounded head, she shares her rumor with her neighbor Cassandra and gets eavesdropped by baby brother Li'l One, who has a grudge on their father. After Ditzy agrees to let Li'l One present the letter to Ma Crumpet, she reads it and angrily bans Pa (who was spotted with Cassie's mother Ms. McBrisk outside) from returning home. Once Granny reveals that the letter and the musicbox belong to her, this rectifies the unjust punishment on Pa.
- The Flintstones
- In one episode Fred's accidental discovery of a poem dedicated to Wilma, as well as Wilma's strangely secretive behavior, make Fred suspect that Wilma cheats on him. The catch is in the fact that the poem was actually written by Fred himself when he was still a high school student, while Wilma was secretive because she wanted to surprise Fred for his birthday. It doesn't help that a man calls wanting to talk to Wilma, and she acts strangely, like she doesn't want Fred to hear. He becomes suspicious and goes to another phone, to hear her say, "...that's right, Darling, not the only man I ever loved, the only man I ever will love." Fred thinks he's about to lose Wilma to another man. It turns out he didn't get to hear the beginning of the conversation, where the man said to her before she responded, "This is the jeweler calling, on your husband's watch for his birthday, you want the engraving to read 'Darling...'" It was at that point Fred picked up the phone.
- In another episode, Wilma suspects Fred of cheating, though with better cause: He's coming home late from work, unusually tired, and when she follows him, she finds him in a romantic nightclub him with a very sexy blonde. The blonde is a charm school instructor, and Fred has been taking courses in dancing, small talk, and related matters so as to make their upcoming anniversary more special and memorable. That night was the final exam/dress rehearsal.
- In a third example, both Fred and Barney fall victim to this trope when they decide to take dance classes so they can take their wives dancing. In order to cover for their classes, they join the "Bedrock Volunteer Fire Brigade", which is a front for the men of Bedrock to get away from their wives; since all buildings in Bedrock are made of stone, all fire alarms are false alarms. Once again, once the truth comes out, Fred and Barney are Easily Forgiven by their wives.
- The backstory for Coldstone in Gargoyles is that "he" was constructed with the remains and souls of three Gargoyles, whom the writers fittingly referred to as Othello, Desdemona, and Iago. Iago wanted Desdemona for himself, and tried to drive a wedge between the couple by convincing Othello that Desdemona was cheating on him with Goliath (making him the Cassio). This misunderstanding was never cleared up prior to their deaths, with the truth only coming to light after a computer virus destabilizes the merger of souls within Coldstone.
- In one episode of Jem Aja mistakes her boyfriend as cheating with Stormer. In contrast to most examples, she believes Stormer and Craig are married while she is the "other woman". It turns out Craig and Stormer are siblings and he was simply afraid to tell Aja earlier because The Holograms and The Misfits get along poorly.
- Justice League:
- In one episode of the Justice League, to prevent ex-employee Rex Mason from exacting revenge for turning him into a shape-shifting mutant, corrupt businessman Simon Stagg shows him a picture of his fiancee being tenderly embraced by his old friend Green Lantern (who was actually comforting her after Rex's mysterious disappearance). Overcome with jealousy, Rex promptly goes to attack Green Lantern.
- In one episode, Green Arrow gets jealous of Black Canary's relationship with the much older Wildcat. In actuality, the two have a father/daughter relationship since Wildcat was teammates with Black Canary's mother.
- Kaeloo: In Episode 83, Mr. Cat lies to Quack Quack that Eugly has been cheating on him, making him paranoid; later in the episode, Stumpy accidentally kisses Eugly, and Quack Quack assumes that this means that Mr. Cat was right and that the kiss was deliberate.
- Averted in Kim Possible. Bonnie, upset at the loss of her boyfriend, forces a kiss on an unwilling Ron. Kim catches them, and, though upset at Bonnie, she completely believes Ron's claim that Bonnie forced the kiss (because, after all, it took years for Ron to kiss her.)
- The Looney Tunes Show: In "Beauty School", Lola sees a woman (actually Bugs in drag) leaving Bugs' house and getting into Bugs' car and immediately assumes that Bugs is cheating on her.
- The Simpsons:
Homer Simpson: "I must be the only gullible husband who ever overheard snippets of surprise-party planning, and believed his wife was having an affair!"
- Another instant was when Homer was returning from France and sees Marge hugging Flanders (she had invited him over for a family dinner). Subverted in that Homer knew that it's probably not what it is. Semi-Double Subversion because they had both been thinking about having an affair but resisted it.
- And there was that episode where Homer and Marge was giving marriage counselling to an idol and her baseball player husband. When Homer gave the idol a backrub while eating chicken, her husband on the other side of the door naturally assumed with the moans they were making that his wife was cheating on him.
- They love subverting this. In another episode Marge listens in on Homer in the next room with his Vegas wife (long story). She hears him says things like, "Oh that's good. Don't stop! Faster, faster! You do this like a pro!" Her response, "Oh no! She's making him a sandwich!" She was.
- In yet another episode, Marge writes a novel that has echoes of real life. Novel-Marge has an affair with Novel-Flanders, which everyone in the town assumes means Marge has the hots for Ned. Lisa is worried that life will imitate art in another way, since in the climax, Novel-Homer character kills Novel-Flanders and himself suffers a Karmic Death. While Homer does chase Flanders to a cliff, it turns out that he just wanted to ask Ned for advice on how to be a better husband, having realized that he's been a real jerk lately.
- In the South Park episode "Insecurity" Ike sees his parents having sex while his father is role-playing, leading him to believe his mom is having an affair with the UPS man. Eventually this information gets to the other men in town and makes them think their wives may be cheating with him too.
- Happens to Reef in the Stōked! episode "Sweet, Sweet Meat Cheat". Fin overhears Reef make a comment about cheating on Lo and assumes the worse. He is actually 'cheating' on the vegetarian diet she put him on by eating franks. During that same episode, Fin running around after Reef and trying to catch him in the act is, ironically, what makes Lo herself believe that Reef is cheating on her with Fin in the first place.
- In the Disney adaptation of The Ugly Duckling the father duck mistakes his mate for cheating once he sees the titular character. The two get into a fight and he leaves. Afterwards the mother duck acts especially harsh to the swan chick.
- The entirety of The Loud House episode "Cheater by the Dozen", which includes Lincoln and Clyde assuming that Bobby is cheating on Lori with other girls including an older woman, a man, and a dog.
- While it doesn't involve actual cheating, a Family Guy Cutaway Gag has Lois catch Peter seemingly having an erotic dream about another woman.
Peter: Oh, Jenny... Jenny... Oh, yeah, Jenny, don't stop...
[Lois sits up in bed and glares angrily at Peter]
Peter: Oh, Richard Jeni, your HBO comedy specials have brought pleasure to millions...
[Lois looks relieved and goes back to sleep]
Peter: ...And what a sweet ass.
[Lois opens her eyes in shock]
- Wait Till Your Father Gets Home dealt with the suspicion of infidelity. Harry is transporting a rather attractive female client to an out of town meeting, when car trouble forces them to stop at a motel. There's only one single-bed room, so Harry insists the client take it while he sleeps in the car. The motel manager suspects some hanky panky until he sees Harry owning up sleeping in the back seat of the car. Irma isn't buying it, believing that Harry is cheating on her. To prove his innocence, Harry drives Irma to the motel where the manager vouches for him.
- A tragic real life example: Rush Dozier in his book Why We Hate, describes an event when a friend of his separated from his wife after several attempts at reconciliation. The man decided to call his wife before moving to another city and an unfamiliar male voice answered the phone. The man rushed to his wife's apartment (it turned out she was alone), broke down the door and fatally shot her, then himself.
- Things can get odd for adult brother/sister siblings who travel or even just go out to dinner together when people who are unaware that the person has a brother/sister sees them out having dinner together or sharing the same hotel room.
- Or relatives of any kind. One family found themselves both amused and dismayed by how many of their friends reported to the wife that they had seen the husband out to dinner with an attractive young woman—his daughter from a previous marriage.
- A woman wrote to Dear Abby to complain about a mysterious young woman who was visiting her married neighbor late at night, being admitted by the husband and later let out. The woman was sure that the man was "sneaking this tart in for sex for his poor wife sleeps upstairs". Reader response suggested that the wife might be fully aware that this young woman was coming over. In fact, the young woman might even be there to see the wife herself. The responses ultimately said that the nosy neighbor was jumping to conclusions, and advised her to butt out.
- This can happen to good platonic friends who happen to be of the opposite gender if they're seen in public together. Some people avoid opposite-gender friendships that aren't mutual with a significant other because of this.