A Deadly Affair

Iago: Your wife's cheating on you.
Othello: She is? (Kills wife) Damn, she wasn't really.

— Book A Minute: Othello

When people have affairs, emotions run hot, especially when someone involved is a little too obsessed or possessive of their partner. Sometimes it leads to someone dying. This trope can happen in a few ways:

1. Killing your spouse: The cheater wants a fresh start with the lover but knows that a divorce will take too long and be too costly, especially in light of their adultery. Or the cuckolded spouse discovers the affair and goes ballistic.
2. Killing your lover: Perhaps the lover wants out. Maybe they are threatening to expose the affair, even asking for some hush money. Perhaps they're pregnant and the panicky husband is afraid that the affair will certainly be found out now. Either way, the cheater gets rid of them for good. The opposite could happen if the cheating partner reneges their promise to leave their spouse for them. It can also happen if the lover was also unaware of their partner's married status.
3. Killing your spouse's lover: Finding out you are being cheated on can be humiliating. Sometimes the cheated-on spouse will seek revenge. If this happens when the spouse is caught in the act, this can overlap with 1 as the cheated-on spouse usually kills both adulterers.
4. Killing your lover's spouse: Sometimes the lover is sick of just being the sidepiece. They want to be their lover's number one girl/guy. So they get rid of the spouse and try to take their place. Also can overlap with Til Murder Do Us Part if both lovers are involved in the spouse's murder.
5. Killing yourself: This is the option taken when Love Hurts. Either there's no way to get their lover, their lover's betrayal cut way too deep, or there's no possible way to repair the damage done to the relationship. Either way, one or more parties decide that they can't live with the pain. A darker possibility is that the person wants to make other people feel responsible for their death, or even frame them.
6. Killing somebody else: In some cases, other people further outside of the main love triangle become involved. Maybe they kill a relative or someone really close to the cheater as a twisted form of payback. Or perhaps someone (like a private eye their spouse hired or their spouse's friend) witnessed them in the act of cheating and goes after them so they wouldn't inform anyone of their infidelity. The latter may usually be done out of desperation or bad judgement.
7. Eliminating the baggage: Probably the most disturbing variety, when someone concludes their object of affection doesn't reciprocate their feelings because they have children. This can drive them to kill their own children, just to free themselves of parental obligation. Even worse, a cheating husband might be inclined to kill either his pregnant wife or mistress. In both cases, to avoid the responsibility of parenthood, and in the mistress's case, to keep the affair from being discovered.

A sub-trope of Destructive Romance. See also Murder the Hypotenuse.

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Examples:

Anime & Manga

• Expecting to Fall into Ruin, I Aim to Become a Blacksmith: When Kururi goes back home on break with his friends including Iris, this prompts Eliza to write him a letter talking about how the capital has been plagued by a murderer who kills men that cheated on their wives. This has the Subtext of her telling Kururi not to cheat on her or else.
• Narciso Anasui of Jo Jos Bizarre Adventure Stone Ocean is in the Green Dolphin prison because he killed his girlfriend and her lover when he caught them together.
• Mars (1996): Rei's mother Shoko was married to Takayuki but was in love with his younger brother Akihiko and the two were in A Family Affair. Though Akihiko dies in an unrelated racing accident, the trope is mostly played straight with Shoko, who kills herself after Akihiko's death as she can't stand the pain of having to live on after Akihiko is gone.

Comic Books

• Batman: Black and White: In "To Become the Bat", a senator with an election campaign coming up has his lover murdered because she's become pregnant and he's afraid she's going to try and blackmail him.
• Sin City: Subverted at the start of "A Dame To Kill For". A wealthy businessman is visiting a particular hooker on the regular but is worried that his wife will find out and financially ruin him in the process. He attempts to kill the prostitute after cuffing her to the bed, only to be prevented from doing so by the timely intervention of Dwight McCarthy, a private investigator who had been hired by the man's wife to track her husband for evidence of the affair.
• Spider-Man: In Sins Past, Gwen Stacy had an affair with Norman Osborn, Peter's worst nemesis. She regretted it, gave birth to twins, and planned on raising the twins with Peter. It was this that caused the Green Goblin to snap and kill her.
• Tyler Cross: One Angola inmate murdered his wife and her lover. Or rather, his lover. In prison, he's been in several other relationships and serves as the accountant (Angola being run as a for-profit prison).
• Wonder Woman Vol 1: Nina Close discovers her husband is having an affair with another woman, whom he likes for having all the traits he literally beat out of Nina. This is the last straw, so Nina creates the identity of the Mask, kills her husband as the mask, and very nearly successfully frames the mistress as the Mask.

Comic Strips

• Calvin and Hobbes: In the 9 December 1985 strip, Calvin gets sick and stays home from school. He watches a daytime soap opera where this trope pops up:
  "Darling": I've got to have you! Let's murder our spouses!
  Mary: Murder?! — You sick animal! I love it when you talk that way! Come here!
  Calvin: [smiling] Sometimes I think I learn more when I stay home from school.

Fairy Tales

• In The Brothers Grimm tale "The Three Snake Leaves", the hero's wife murders her husband after cheating on him with a skipper.

Fan Works

• but i wrote the words to the swan song: Subverted. The Ottoman dignitary that fell in love with Juliet offers to have his wife killed just so he can marry her. Juliet tells him that she'll settle for being his mistress, thus it's implied the dignitary's wife is spared as a result.

Film — Animated

• Justice League: The Flashpoint Paradox: The main reason the setting is such a Crapsack World is that Aquaman's wife Mera caught him in bed with Wonder Woman. Mera was killed in the ensuing confrontation, and Aquaman declared war on the Amazons.

Film — Live-Action

• This kicks off the plot in Andhadhun. Simi and Manohar, who are both married to other people, have an affair. When Simi's husband Mr. Sinha comes home to surprise her on their anniversary after having told her he was going to Bengaluru, they are found out. Mr. Sinha ends up dead, though it is ambiguous exactly what happened. Did Manohar or Simi kill him? Did the gun go off accidentally, as Simi later claims? Or did he shoot himself when he saw his wife with another man?
• Asylum: In "Frozen Fear", Walter murders his wife so he can run off with his young mistress Bonnie.
• The Beta Test: A running motif in the film is people getting killed by their significant others over the affairs they were lured into by the purple envelopes. We see a few of these murders take place, and there are messy breakups in the background of several other scenes.
• Boogie Nights: Little Bill has twice caught his wife in flagrante delicto with another man. Both times, she's unperturbed about it, actually shooing Bill away to continue the tryst. At a New Year's party, Bill again discovers his wife bumping uglies with another man, pulls out a snub-nosed pistol, and shoots his wife and her lover dead. He then glumly ambles away, and as the revelers count down the seconds to the New Year, puts his gun barrel in his mouth and blows his brains out.
• The Cat's Meow: Hearst (rightly) suspects that something is going on between Marion and Charlie Chaplin. He plans to Murder the Hypotenuse by killing Chaplin, but instead commits Murder by Mistake when he shoots Thomas Ince, who happens to be wearing Chaplin's hat.
• The Children Are Watching Us: Andrea's wife Nina cheats on him, leaves him, comes back, then cheats on him and leaves him again. Unable to bear the social stigma (it's 1942 Italy), Andrea kills himself.
• Con Air: The backstory of William Bedford a.k.a. "Billy Bedlam". After catching his wife in bed with another man, Billy pulls a Revenge by Proxy leaving his wife and her lover alone but instead kills his wife's parents, brothers, sisters, and even the dog just to get back at her.
• Confidentially Yours: One of the reasons Vercel is suspected of murdering Massoulier is because the latter was having an affair with his wife. She's later found murdered, which worsens Vercel's case.
• In The Conversation, Harry pieces together bits of audio he recorded from a young couple to find out that they're worried about the woman's rich husband killing them before they can run away together. Except that Harry was mistaken, and they were actually talking about their own plot to kill the husband. They end up succeeding.
• In Dial M for Murder, tennis star Tony Wendice discovers his wealthy wife Margot is cheating on him with crime author Mark Halliday. Initially, Tony responds by recruiting his old Con Man friend Swann to murder her. Unfortunately for Tony, Margot is able to kill Swann in self-defense just when it seems she's done for. Once he finds out, Tony switches gears and tries to frame her for murdering Swann instead.
• D.O.A.: Played with in the 1988 remake. The police and Professor Cornell all assume that Nick Lang & Professor Cornell's wife's murders must be related to the affair that Nick and Cornell's wife were having. The various suspects include Cornell (furious at being cuckolded by his own student), Nick's adoptive sister (in love with Nick) or Nick's adoptive mother (initially implied to be in love with Nick). It actually turns out that the affair is completely unrelated to the murders.
• Double Indemnity: Phyllis Dietrichson arranges her husband's death with the help of her lover and insurance salesman Walter Neff, to cash in on the policy they filled behind his back.
• Eve's Bayou: Eve's father Louis Batiste is constantly cheating on his wife with the various female patients he makes house calls on and the equally promiscuous Matty Moreaux, who sleeps around while her husband is out of town. Matty's husband Lenny finds out and drunkenly confronts Louis, ordering him not to say another word to his wife or he'll kill him. Louis mockingly says "good night" to Matty and is shot dead in front of his horrified daughter Eve.
• The Hazing: The legend of Hack House says that Jeremiah Hackford snapped after discovering his wife in bed with the stable boy, and he went on a rampage where he slaughtered everyone in the house before killing himself.
• Indict And Convict: The made-for-TV drama opens with discarded clothes on the carpet leading to the bedroom, where the lovers are flagrante delicto. Gunshots are fired, and the ensuing double homicide investigation focuses on the cuckolded husband: he's the leading assistant prosecutor for the District Attorney's office.
• In Judas Kiss, Becky Hornbeck is killed as she is coming to her lover's apartment in what appears to be a case of Accidental Murder. However, as the investigation progresses, both Agent Hawkins and Det. Friedman start to suspect her death may not have been so accidental, and that her affair may have been the real trigger.
• Le Bonheur: Therese kills herself after finding out her husband is having an affair with another woman.
• Minority Report: In the Action Prologue, John Anderton foils an attempted murder by a man who suspected his wife of cheating on him and caught her in the middle of the affair, trying to stab both his wife and her lover with a pair of scissors.
• In The Naked Witch, the innkeeper is having an affair with the widow while his wife is sick. However, when the widow starts demanding that he put aside his ailing wife and marry her, he accuses her of witchcraft and has her executed.
• A Perfect Murder: Steven's first plans to murder his wife Emily, who's cheating on him with David, involves blackmailing his wife's lover to execute this murder. It doesn't go according to plan, as Emily accidentally kills David instead of the other way around. In the end, Steven outright tries to murder Emily himself, but it also turns out that, even more than for her affair, he's murdering her for her (rich family's) money.
• Pitch (2009): After discovering his wife's affair, Gene takes a gun and approaches the bedroom where she's sleeping with her lover, intent on shooting them both.
• In The Prowler (1951), Webb and Susan are having an affair, but Susan soon ends their relationship, choosing to remain with her husband, John. However, Webb's obsession with her continues to grow, until he begins plotting to kill John and cash in on his life insurance policy.
• An affair is revealed to be the catalyst of the events of Red Riding Hood, which ends with at least a dozen people dead. Suzette cheated on her husband Cesaire, who unbeknownst to most people, is a werewolf. Suzette got pregnant and claimed the baby, Lucie, was Cesaire's. He eventually intended to give both his daughters the 'gift' of lycanthropy during the blood moon (the only time new werewolves can be made), but when he tried to telepathically communicate with Lucie in his wolf form, she couldn't understand him and he realized she was Not Actually His Child. Enraged, Cesaire killed Lucie, killed Suzette's lover, and then went on a murderous rampage around town, demanding that his biological daughter Valerie leave with him or else.
• The Shawshank Redemption: Andy is sent to prison for murdering his wife and her lover. He maintains that he is innocent and that he threw his gun into the river instead of shooting anyone with it. Later, it's revealed that Andy really is innocent. The murders were committed by a burglar who was there to rob the lover's house.
• In Shock, Dr. Cross asks his wife Margaret for a divorce so he can marry his mistress Elaine. she agrees to the divorce, but promises to drag his name through the mud in the process and destroy his reputation. Cross snaps and grabs a candlestick and bludgeons her to death with it.
• The opening scene of A Shot in the Dark establishes that every single member of the Ballon household is secretly having an affair with at least one other member of the household. This complicated tangle of infidelity sets in motion all of the murders which are not the accidental byproduct of Chief Inspector Dreyfus' efforts to get rid of Clouseau.
• Unfaithful: Loving wife Connie starts having an affair with a handsome young hunk named Paul. Her husband Edward learns about the affair and confronts Paul, leading to the latter's murder. While in Paul's apartment, Edward overhears a voicemail that Connie leaves breaking off their affair, and when Connie finds out about the murder, she decides to help her husband cover it up. The film ends with them sitting in their car crying, near a police station; they know that for the rest of their lives, they'll be living in fear of being caught.
• What Lies Beneath: The reason that Madison haunts the Spencers is that Norman was cheating on Claire with her. He killed her when she threatened to go to university authorities about their relationship, which would have likely gotten him fired and ruined his reputation.
• Who Framed Roger Rabbit: Played with. The eponymous animated character is framed for committing murder after viewing photos taken of his cartoon wife literally "playing pattycake" with a human man.

Jokes

• A Dumb Blonde joke has the blonde come home from work early to find her husband in bed with another woman. She yells "I knew you were cheating on me!", takes a gun out of her purse, and puts it to her head. The husband begs her not to shoot herself and she replies "Shut up. You're next."
• A man is standing trial for the murder of his adulterous wife.
  Judge: Tell me, why did you, when you caught your wife in bed with a lover, kill her instead of him?
  Husband: Your honor, I decided it would be better to kill a wife once than a lover every week.
• A man confesses on his deathbed to his wife/girlfriend that he cheated on them. His wife/partner replies, "It's OK, dear, I already knew that. That's why I poisoned you."

Literature

• In Alex Cross novel Cross the Line one of the plots involves the murder of police captain Tom McGrath and his girlfriend Edita. The culprit was Alexander Gordon, the lover of McGrath's estranged wife Vivian, who kept their relationship secret because he was her divorce attorney. Due to losing money to a bad investment, Gordon planned to set up a memorial charity with Tom McGrath's life insurance policy and steal from it. When exposed Gordon kills Vivian, holds Detective Bree Stone hostage, and is shot by her partner Mueller.
• In And Then There Were None, General MacArthur is accused of sending his wife's lover to his death. This is subsequently confirmed by the narrator when talking about the General's thoughts.
• Francesca and Paolo from The Divine Comedy were two nobles who had an affair that ended when Francesca's husband killed both of them, sending the two of them to Hell for lust.
• Paul of The Green Mile tells about a female inmate, Beverly McCall, who accepted being beaten by her husband but who, upon learning he cheated on her, took a razor and cut his genitals, leaving him to bleed to death.
• In Let Me Call You Sweetheart, one theory about Suzanne's murder is that she was killed by her possible lover, or that her husband killed her out of jealousy she was seeing someone else. It's eventually revealed her lover killed her for refusing to give back jewellery he'd given her, and for flaunting her new boyfriend.
• In 'Salem's Lot, it's mentioned that one of the town's residents murdered his wife when he found out she was having an affair with a travelling salesman. Everybody else thought she had left with the salesman.
• The Screwtape Letters: Discussed by Screwtape, as he gives Wormwood advice about how to incite a type of human lust that can lead to adulteries that, in his own words, end, "if all goes well, in murders and suicides".
• Sherlock Holmes supposedly has this in his backstory, chronicled in the non-canon The Seven-Per-Cent Solution. Holmes is brought to Vienna, Austria to meet budding psychologist Sigmund Freud, in an effort to treat Holmes for cocaine addiction. There, Freud discovers that Holmes's mother was caught with a lover by his father, who murdered the pair for their infidelity. It was young Holmes's mathematics tutor, Professor Moriarty that delivered the horrible news to him. Thus, concludes Freud, Holmes developed his dogged justice-must-prevail ethic, and his vilifying Moriarty is a Shoot the Messenger coping mechanism.
• Simon Ark:
  • The motive for murder in "The Man Who Shot the Werewolf" turns out to be a high-profile politician discovering that his wife was having an affair with a much younger man. The werewolf story was something that the politician, an experienced hunter, concocted as part of an elaborate double-bluff cover-up.
  • In "The Weapon out of the Past", one half of an adulterous couple decides to murder the wife of her lover and make it appear to be supernatural.
• Tortall Universe: In Beka Cooper, one of the women Kora investigates as a victim of the Shadow Snake turns out to have drowned her child in order to get with a man who didn't like kids, then told her neighbors it was the Snake. She is later magically compelled to walk into a police station and confess to everything, which Kora had nothing to do with (Kora's sister was murdered as a child, and she hates all child killers because of this).
• In Where Are the Children?, the prosecution convincingly argued that Nancy killed her children so she could run off with her lover, Rob Legler. The lead prosecutor even believed Rob was complicit and would've charged him as an accessory if there was enough evidence. However, Nancy didn't actually kill her children, nor was she having an affair with Rob, despite him attempting to put the moves on her. He didn't kill her children, either.
• You Don't Own Me: Due to Kendra's claim that her husband Martin was having an affair with Leigh Ann, it's speculated that Kendra or Leigh Ann's husband Daniel could've had Martin killed for revenge, although everyone but Kendra and Steven (who is obviously in love with Kendra) insists there was no affair. Leigh Ann and Martin were having an affair, but while Martin treated the relationship seriously and wanted to leave his wife for Leigh Ann, she only viewed the relationship as a temporary distraction because she was bored and lonely; she had no intention of leaving her husband, nor any interest in playing stepmother to Martin's kids. Martin didn't take this well and kept pushing Leigh Ann to leave her husband, including threatening to tell Daniel and the media (the latter of which could've derailed Daniel's political career and Leigh Ann's own ambitions). This prompted Leigh Ann to permanently silence Martin and let his wife take the blame.

Live-Action TV

• The Afterparty: Discussed and double-subverted in the seventh episode. Danner says that 90% of daytime homicide cases in the posh California neighborhood they patrol are domestic affairs. She's surprised when the most likely suspect is a package thief, but later realizes that it was a husband impersonating said package thief to kill his wife...because he was having an affair with a coworker.
• Banjun Drama: This turns out two different ways in "Fatal Love." While the main character Jin, his boss (Kyung-seok), and his boss's wife with whom he'd fell into a love affair with (In-young), confront each other, Jin hits his boss's head with a book, and the impact seems to kill him. Though In-young is traumatized, Jin advises her to pretend nothing ever happened. Later, In-young sees an apparition of her husband in the middle of the night and promptly dies of a heart attack. But the heart attack was all part of Jin and Kyung-seok's plan - the two planned the fake death, and even the whole affair between Jin and In-young, for money and... love. Because Jin and Kyung-seok were in love the whole time.
• Castle:
  • "Hell Hath No Fury": The murder of a city councilman running for reelection ultimately traces back to his wife, who killed him when she discovered he was having an affair.
    Beckett: Why is it always the family values guys who get caught with their trousers down?
    Castle: Because the universe loves irony. And because most people are hypocrites.
  • "A Deadly Game":
    • Castle and Beckett investigate the murder of a man taking part in a spy LARP vacation, using it as a cover for meeting up with his mistress. The killer turns out to be her husband, whereas the victim's business partner ironically alibis out on grounds of he was in bed with the victim's wife at the time of the murder.
    • Also discussed in the same episode by the Genre Savvy guests at Castle's crime novelist poker game.
      James Patterson: If I was writing this, the murder would have nothing to do with the spy game, except that it gave the killer an opportunity to act.
      Michael Connelly: Knowing that the trappings of the game would cover his tracks.
      Stephen J. Cannell: Which is pretty much what's happened. Look, Rick, as much trouble as we go to with these novels, there's only three reasons to commit a murder: love, money, and to cover up a crime.
• Colonel March of Scotland Yard: In "Death in Inner Space", a scientist discovers that his assistant is having an affair with his wife. He murders the assistant by sabotaging the breathing apparatus being used in a space flight simulation.
• Criminal Minds:
  • Season six episode "Compromising Positions": The first victim of the killer's career was the man that impregnated his wife. When talking to the wife Reid shows her pictures of male murder victims and, despite Rossi and Hotch's skepticism, she turns on her husband when she sees the photo of the man who fathered her child.
  • Season ten episode "The Witness" has Charlie Senarak go after the man his wife was sleeping with. When he confronts the man, a struggle ensues, and Senarak kills the man. The man's half-brother, anti-government terrorist Mitchell Crossford, blackmails Senarak with this knowledge and tries to frame him for a sarin gas attack.
  • During season twelve Reid is sent to prison for a crime he did not commit. There he meets Calvin Shaw, a former FBI Agent who murdered his confidential informant. He claims that she was blackmailing him, but he actually was having an affair with her and killed her to prevent her from speaking and to destroy evidence of her pregnancy.
• CSI-verse:
  • One episode of CSI had one team investigating the deaths of two baristas, a casino magnate, his bodyguard, and a college student who was there doing some homework. The evidence eventually leads them to a local businessman, who after being confronted with the findings of the CSIs' confesses to the crime. He was having an affair with one of the baristas, and when she became pregnant, he promised to cover the costs of the abortion, so long as his wife didn't find out. As the months progressed, she changed her mind and decided that she was keeping the baby and suing him for child support. In a fit of rage, he shot her dead, when her coworker went to investigate, he shot her as well, and when the casino magnate went in to buy some coffee, his bodyguard was gunned down as he reached for his gun, then the magnate was killed. The college student, whose earphones drowned out the sound, was also killed.
  • One episode of CSI: Miami has this as its big reveal. The victims in a double murder are the parents of a teenage girl. The girl's boyfriend killed her father, and the girl arrived in time to see her mother telling the boyfriend that because of what he did, "We can be together now" - he had been sleeping with the mother. Enraged, the girl killed her mother. When the shock wore off, the two teenagers agreed to keep silent.
• Death in Paradise: In "Death in the Salon", the murderer is having an affair with her younger sister's fiancée and murders the Victim of the Week who threatens to expose it.
• Diagnosis: Murder: In one episode a woman kills her lover in a fit of rage after learning he's been unfaithful.
• Elementary:
  • Season two episode "The Grand Experiment" has Sherlock hunting down a mole in the MI-6. He notes that all of the communications between the mole and his contact, Julian Afkhami, caused political consequences except for one of them. Sherlock realizes that it instead had local consequences, the mole let the Afkhami know his wife was cheating on him, resulting in Afkhami hunting down and stoning the lover to death. This backfires when Afkhami's wife saves his bloody undershirt from the fire, resulting in his conviction.
  • During the backstory of the season four episode "For All You Know", a city councilman kills a woman who he was having an affair with. A cleaning lady sees him disposing of bloody clothes and tries to get Sherlock to help. Since Sherlock is addicted to drugs, he is unable to help and the woman is murdered too. In the present, Sherlock himself is accused of committing the crime.
  • Season six episode "The Worms Crawl In, The Worms Crawl Out" a murdered professor is discovered to have had many affairs with students and fellow professors. The husband of one of them admits to shooting the victim, claiming he forced his wife into the affair. The fact that the victim died from a stab wound makes the investigators realize the victim was wearing a prototype bulletproof jacket, the motive of the actual killer.
• Interview with the Vampire (2022): In the Season 1 finale, the Love Triangle between Louis de Pointe du Lac, Lestat de Lioncourt and Antoinette Brown finally comes to an end after 23 years when Louis kills his abusive boyfriend and the latter's side chick. It's the only way Louis can escape from Lestat's Gilded Cage and an eternity of being the latter's Property of Love, which will soon also include Lestat forcing Louis to be his Gender-Inverted Top Wife in a Vampire's Harem. Lestat's control over Louis would be absolute in this scenario because Antoinette, now a vampire and Lestat's soon-to-be second wife, can telepathically monitor Louis' thoughts and inform Lestat if Louis wishes to flee or commit suicide. To avoid this everlasting hell, Louis murders them both.
• iZombie:
  • A complicated case in season 3. A girl was sleeping with her stepfather, who was married to her mom. When the girl's friend's father found out, they decided to take it to the authorities, since she was underage. Thanks to a spy app, the girl's mother found out about it and killed her daughter's friend and her father, and then attempted to frame her husband for the murder.
  • Season 3 has the murder of a womanizing kindergarten teacher, who had affairs with several of the mothers of the children in his class, being killed in the night all of them found out about each other. It was the husband of one of them, that had contracted a private eye to find out who was sleeping with his wife and then went to his house and killed him.
  • In "Eat A Knievel", the motive of the murder of a stunt artist that played a lot of pranks was that he seduced, slept, and impregnated the fiance of a member of his crew.
• Monk: A lot of murder motives involved adultery in some fashion, either to remove relationship obstacles or because the paramour threatened to embarrass them in some way.
  • Two episodes (Mr. Monk and the Airplane and Mr. Monk Goes to Vegas) involve a man who has a lover who's a dead ringer for his wife, and they conspire to murder the wife and use the lookalike mistress to pretend she's still alive long enough to obfuscate investigation.
  • Mr. Monk and the Girl Who Cried Wolf centers around a woman and her lover who plot to kill the woman's husband and gaslight Sharona into thinking she's crazy so she can get away with using the murder method Sharona came up with for a book.
  • In Christmas Episode "Mr. Monk and the Secret Santa" the perp killed her lover, a fellow officer at Stottlemeyer's precinct when he decided to reconcile with his wife. Her plan involved sending Stottlemeyer a bottle of poisoned wine she knew he didn't like, knowing that Stottlemeyer would give it to her lover, who did like that type of wine.
  • In Mr. Monk and the Astronaut, the victim of the week was murdered when she was about to write a memoir that revealed her affair with the titular astronaut (and, more pertinently, his abuse of her).
  • In Mr. Monk Fights City Hall, Councilwoman Hill was killed by her lover when she pretended to be pregnant to force him to leave his wife for her.
  • Trudy Monk's murder turns out to be an extremely long-term version of this. The victim had an affair with their law teacher when they were in college. Years later, the teacher, Ethan Rickover, became a judge and feared the scandal of the affair being found out (and by extension his murder of the midwife present when she gave birth), and so hired a thug to kill the student. In the meantime, Trudy (the student) had married Detective Adrian Monk, and recorded a video message confessing about the affair just before she was killed. When Monk finally works up the courage to open her last gift, he's able to pin Rickover for the crime.
• Justice Served: Murderous Affairs: This documentary series shows that this trope can be Truth in Television. Each episode follows two incidences of a cheating spouse and their lover plotting to kill so that they can either run away together or spend the victim's life insurance, then a reconstruction is shown of the plan either succeeding or not, and then the eventual jail sentences — many of them being life without parole.
• The 2023 limited series Obsession combines this trope with A Family Affair. The main character begins an affair with his son's girlfriend (and later, fiancée), his son discovers the affair in the final episode and ends up jumping to his death, resulting in the lives of every surviving character being in tatters.
• In the pilot episode of Perception (2012), the chief legal counsel for a pharmaceutical giant is beaten to death with a trophy. His wife confesses, although her severe Korsakoff syndrome makes her confession worthless. It turns out that the man was having an affair with a lab worker, which Moretti sees as a plausible motive for the wife. The trope is in play, but in the other direction. The two lovers were slowly poisoning the wife, which is what caused her Korsakoff syndrome. Meanwhile a researcher beat the husband to death for unrelated reasons.
• Person of Interest: A time-delayed version where Gianna Moretti has a henchman kill his lover Marlene Elias. He later tries to kill her son Carl, who meets him and tried to work for him, not aware that he had his mother killed. This is what drove Carl Elias to become a powerful crime boss, and killing Gianna Moretti, his son, and the other Mafia Dons.
• Probe's
  • "Untouched by Human Hands": When Brian Kingsley tries to fake his death, he sneaks in a homeless man, has one of the robots kill the guy, and dresses the victim up in his own clothes. This is all to allow him the chance to run away with his housekeeper and his two point five million dollars life insurance policy.
  • "Quit-It": Julie, the married woman, kills Lou, the married man she's having an affair with. She's been Brainwashed by her son into killing him.
• Small Sacrifices: The made-for-TV movie recounts the investigation of a triple homicide in Oregon. Diane Downs is a divorcee, seeking to hook up with a married coworker. Though interested, the man won't break off with his current wife just for Diane. Diane concludes that her three children are impeding her progress, and takes them on a car ride along a lonely farm road, where she shoots them. It's a Dramatization of an actual crime from May 1983.
• Vera: In "Vital Signs", infidelity looks like the obvious motive when Vera and her team discover the married Victim of the Week was having an affair with a married co-worker. However, over the course of the investigation, several other strong motives for murder turn up. Ultimately, the affair was the reason she was killed, but Vera has to work out which of the multiple aggrieved parties was responsible.
• Veronica Mars:
  • Aaron Echolls nearly becomes a victim when one of his mistresses becomes a Woman Scorned when he tries to ignore her and stabs him in public.
  • Aaron Echolls turns out to be a perpetrator of this as well when he turns out to be the one who killed Lilly Kane to cover up his affair with her.
• The X-Files episode "Familiar" has a woman discovering her husband has been having an affair with another married woman. So, she turns to witchcraft to kill him. It works, but not before their daughter and the son of the mistress are also killed by the dark forces. The ensuing chaos also leads to her husband killing the mistress' husband and the mistress dying in a car accident. Then, she spontaneously combusts for good measure.

Music

• Garth Brooks:
  • In "Papa Loved Mama", a long-haul trucker returns from a run to find his wife is down at a hotel with her lover while his children are left home alone. He chooses to drive his eighteen-wheeler into their hotel room, killing his wife and sending himself to jail.
  • The live-only fourth verse of "The Thunder Rolls."
    She runs back down the hallway and through the bedroom door
    She reaches for the pistol kept in the dresser drawer
    Tells the lady in the mirror, "He won't do this again
    'Cause tonight will be the last time, she'll wonder where he's been"
• In "I Ain't Done" by The Crane Wives, the singer sneaks out while her spouse is asleep to sleep with her lover, only to be found out by her spouse one night, resulting in both the singer and her lover being murdered that night. In the afterlife, singer declares that she has no regrets for being "a woman in love" and has all the time in the world to repent if she has to.
  Felt love's searing sting
  You exposed my nightly wanderings
  You put me in the ground
  But I ain't done
• The third verse of the Eminem and Dr. Dre song "Guilty Conscience", in which the two play Good Angel, Bad Angel, has the two speaking to Grady the construction worker who just walked in on his wife cheating on him; Eminem attempts to talk Grady into killing them both, while Dre attempts to talk him out of it. Not only does Eminem convince Grady to go through with it, he convinces Dre to agree it's what should be done.
• Performed by multiple artists but perhaps most notably by Jimi Hendrix, "Hey Joe" has the title character answering a friend's questions. Where is he going with that gun in his hand? He's going to shoot his wife after he caught her cheating on him. Did Joe really shoot her as his friend heard later? Yes, Joe admits to doing exactly that. What's next for Joe? He's making a Run for the Border to escape justice.
• Tom Jones' hit "Delilah" is about a man who murders the titular woman after he catches her cheating on him with another man.
• The Vick Lawrence hit "The Night the Lights Went Out in Georgia" has the main character go after his friend for being one of the people cheating with his wife and ended up finding the friend already dead. It turns out the singer, the main character's little sister, was the one who killed the friend and also the wife, but got away with murder since the main character got caught.
• "Wake Up Call" by Maroon 5. The main character catches his girlfriend in bed with another man and shoots him.
• In the Melanie Martinez song "Sippy Cup", Cry Baby's mother has murdered both the father and his mistress, with the lyrics being all about how the mother is trying to cover it up and forget about it — even though she really can't.
• Taylor Swift's evermore: In "no body, no crime", Este is implied to have been killed by her husband after she discovered his affair.
• "Two Black Cadillacs" by Carrie Underwood is about a woman whose husband cheated on her, and his mistress who was unaware he was married, working together to kill him.

Religion and Mythology

• In Arthurian Legend, Arthur is planning to have Guinevere executed after her affair with Lancelot is revealed. Modern takes often present this as something that he doesn't want to do, but her actions constitute treason, and his own rules say that nobody, even the queen, is above the law. Lancelot rescues her, which makes things much, much worse.
• Classical Mythology:
  • This is a running thing with Hera. Granted, she doesn't always kill Zeus' mistresses or illegitimate children, but she'll find some way to make their lives miserable.
  • Jason married Medea, but then opted to put that marriage aside for a princess so that he could move up in the world. Medea responded by killing the other woman, as well as her and Jason's sons. Depending on the Writer, the latter was either a deliberate move to hurt him, or did this after belatedly realizing that they would get sold into slavery for her actions.
  • The whole Trojan War was, in part, done so that Menelaus could get the adulterous Helen back to kill her. After the fall of Troy, however, he finds himself unable to destroy her beauty, and the two instead opt for an eternity of passive-aggressive matrimony.

Stand-Up Comedy

• Discussed by John Mulaney in The Comeback Kid:
  I would always think to myself... how could a human being kill another human being? And then I got cheated on and I was like, "Oh, okay. I'm not gonna do it, but I totally get it." And I don't mean in that way of, like, "No one else can have you". It's just creepy to have an ex out there after things have ended badly. They have a lot of information. Anyone who's seen my dick and met my parents needs to die.

Theatre

• In Chicago:
  • Roxie kills her lover when she finds out he was not going to help her become a singer.
  • Velma kills her sister and husband when she finds them in bed together. This applies to four of the other "Six Merry Murderesses" featured in "Cell Block Tango" — one killed her lover after finding out he was already married, another killed her husband when he confronted her about her affair, another killed her lover after his numerous infidelities, and even the unjustly imprisoned woman is accused of conspiring with her lover to kill her husband.
  • A rich heiress kills her husband and the two women he was having a threesome with.
• Pagliacci: When Canio discovers his wife Nedda is having an affair, he kills her and her lover on stage in the middle of an In-Universe performance. The audience initially thinks Canio's declaration that he is no longer Pagliaccio is all part of the show but when he stabs Nedda, they realize it's real.

Video Games

• As Far Cry 4 progresses, it's revealed that Ajay's mother had an affair with Pagan Min. As a result, they had a daughter together who was killed by Ajay's father. His mother killed him in revenge and fled the country with Ajay.
• The backstory of The Letter has this incite the plot. Lady Charlotte Ermengarde was caught cheating on her fiancée Eduard by her maid Takako, and had her tortured for it; when Eduard discovered this, he tried to leave her, driving her to murder him in front of Takako and frame her for it, getting her executed. It then turned deadly for Charlotte herself as Takako came back as a Vengeful Ghost and drove her to suicide.
• In Metropolis Lux Obscura: Reuniting with Goldie results in Goldie shooting Lockhart point-blank in the head for all the times that he cheated on her.
• The tutorial of Prison Architect involves Edward, a prisoner sentenced to death for shooting his unfaithful wife and the man she was cheating on him with dead.
• The Walking Dead: Season One: Lee's wife cheated on him with a state senator, and he killed the new man in response, leading to his murder conviction. Things went downhill from there.

Webcomics

• In I Love Yoo Rand and Nessa's affair ends up with her dead, although the cause is still unclear.
• In The Order of the Stick, has a Shoot the Messenger variation. The Oracle gets killed now and then by clients who don't like the predictions he gives them, though he fortunately can arrange his resurrection well in advance. According to him, the next time he dies would be when a big druid tears him apart after confirming to him that his wife was cheating on him (with his intelligent-boosted animal companion yet).

Web Animation

• The Black Cat's Lair: Monica killed Colin's wife Dani to get with him since she was having an affair with Colin. She even planned to kill his son since she saw him as a bully and a spoiled brat.
• Etra chan saw it!:
  • Yuzuriha attempts to kill her lover's daughter, Tsutsuji, by giving her pieces of glass shards she passes off as candies to make him and his wife divorce so she could be together with him.
  • Tachibana finds his girlfriend sleeping with another man, causing him to assault the lover until his girlfriend hits him with a bottle due to her life being threatened, he ends up dying from the injury.
• Helluva Boss Season 1 Episode 1 opens with A Tragedy of Impulsiveness where Mrs. Mayberry, a teacher who has been a good person all her life, immediately snaps and commits Murder-Suicide when she discovers her husband cheating on her and ends up in Hell for it. She hires I.M.P. to kill her husband's mistress who survived the Murder-Suicide because it is unfair that people are now calling her a hero for her survival. And this is all before we learn what the mistress and her family are up to.

Web Original

• Black Jack Justice:
  • The third episode, "Justice is Blind", features Jack and Trixie doing multiple weeks of stakeout on a man's wife and her lover. The husband, after great reluctance, asks for photographs of the affair to have solid proof. When they do just that, Jack and Trixie see the lover depart but not the wife. After several hours Jack goes to check and discovers the wife murdered. It's not long before Jack realizes that the whole thing was a set-up by the husband, meant to use the photographs Jack and Trixie took of the lover leaving to frame him for the crime.
  • The episode "Hush Money" has the detectives' more straight-laced associate, "Button-Down" Theo, enlist their aid in a case that involves paying off a blackmailer. The man doing the paying, Douglas Rose, is hesitant to go into specifics, saying only that the money is to deal with his past indiscretions. When a baby starts crying during the hand-off, the detectives discover during the drop that they aren't paying off a blackmailer, they're paying contract killers who were indeed going deal with Rose's "past indiscretion", mother and child both.

Web Videos

• The Human Pet: Eric had an affair with his boss's wife Sue, which is told about in vlog files leaked by The Codemaster. The details aren't elaborated upon, but it's heavily implied that as a result of the affair, either he or Sue committed murder after they realized her husband had cameras all over the house. Who died isn't revealed, but it's mentioned that Eric had to deal with police interrogations and that Sue blamed him for what happened.

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