Someone murders their significant other as vengeance for adultery.
Alice is dating or married to Bob. Alice finds out that Bob is sleeping with Carol. Alice then kills Bob for cheating on her. This may be presented as a justified act, even if it is a serious crime. He'd done her wrong. While the same scenario is a common dramatic plot with both genders, modern depictions are often more sympathetic to Alice shooting Bob-the-cheater than Bob shooting Alice-the-cheater.
In Real Life many cultures have tended to go easy on the husband's killing either a cheating wife and/or the man she was cheating with. Not so much in the modern Western world, though, and stories produced from that perspective don't usually treat it as justified in anything more than a passing reference/joke, which is why most examples here come from songs. A full story involving someone killing their straying lover usually has to admit that this is a bad thing to do.
See also Woman Scorned, If I Can't Have You..., Yandere, and Murder the Hypotenuse. See also Manslaughter Provocation - until 2009, in Britain, killing your partner for infidelity was manslaughter, not murder. May overlap with Asshole Victim if the deceased was particularly unsympathetic (e.g. if he habitually mistreated her in other ways).
As a Death Trope, all Spoilers will be unmarked ahead. Beware.
Woman kills Man
- This is the setup for the Roald Dahl short story "Lamb to the Slaughter", infamous for its extremely clever Twist Ending. Admittedly, it's stepped up a notch as the husband explains to his wife — who's pregnant with their first child — that he's going to leave her for reasons implied to be this trope, ending with "And I know it's kind of a bad time to be telling you, but there simply wasn't any other way. Of course I'll give you money and see you're looked after. But there needn't really be any fuss. I hope not, anyway. It wouldn't be very good for my job." You might be tempted to konk him too.
- In Stephen King's The Green Mile, there was only one woman on the Mile, who put up with her husband beating her every night, but killed him the moment she heard he was cheating on her. Her sentence was commuted to life and she died a free woman.
- Murderess features a narrative poem about a girl who takes bloody revenge against a former lover, sneaking into his room, cutting his throat, and telling him how happy she will be knowing he's dead.
- In Susan Dexter's The True Knight, the opening scene is when the queen, having killed the king who sent her away to bring out his mistress openly, now goes to kill his mistress and their daughter. (The daughter is only saved by a Baleful Polymorph.)
- In No Way to Treat a First Lady by Christopher Buckley, Elizabeth Tyler MacMann is indicted for murdering her husband, the President of the United States. The last night he was alive, she confronted him over his latest infidelity and left a mark on his forehead with a Paul Revere soup tureen. Subverted when the actual cause of the President's death is determined to be heart failure induced by an overdose of Viagra.
- In Warrior Cats, Mapleshade murders her unfaithful mate Appledusk. Subverted in that this is only part of her motive; she also does so to avenge their kits whose deaths he blamed her for.
- This trope is the entirety of the Oxygen Channels's Snapped. Most episodes covers a Real Life case of an abused and/or cheated-on woman who killed her husband (sometimes father). They try not to paint the women in a sympathetic light, but the show still has a "You go girl" kind of feel.
- Sometimes the husband is a saint and the woman is simply tired of being married but doesn't want to go through a divorce, or wants his life insurance policy, or the woman was actually a sociopath. These episodes don't count, though - they're just plain ordinary murder and not relevant to this trope. Women do sometimes kill people for reasons other than "bad men".
- Since Orange Is the New Black is about a female prison, some of the inmates who are in for murder are perpetrators of this trope.
- We don't know about the man whose penis Frieda cut off with a butcher knife, but if he survived, he would possibly wish this trope was played straight in his case.
- Cher's "Dark Lady." Here, the main protagonist is a woman who visits the title character, a fortune teller, distressed over a failing relationship with her boyfriend. Unknown to the woman, the boyfriend has been cheating on her and that his lover is the "Dark Lady," although this is not made clear until the end of the song. Using foreshadowing, it is clear that "Dark Lady" becomes nervous over her visitor so, after the rigamarole of dealing cards and mumbling incoherently into a crystal ball, draws two cards, gives the vague clue that the boyfriend has indeed been unfaithful and his lover is "someone else who is very close to you," and then advises her to leave and never return ... even forget that she even visited. The woman goes home and tries to get some sleep. Until she accidentally gets a whiff of the smell of the room ... it was perfume that was identical to the scent she got at the fortune teller's hut. Curious and wanting answers, she makes a return visit to the Dark Lady ... and because she is suspicious as to what is going on, brings along a gun. Those suspicions are confirmed when she walks into the back area of the hut ... and finds the boyfriend and "Dark Lady" in each other's arms having sex. They're in a state of sexual ecstasy ... until they see the boyfriend's angry girlfriend pointing a gun at them ... and the gun is loaded ... and it is fired.
- Three of the "Six Merry Murderesses of the Cook County Jail" from "Cell Block Tango" fall under this trope.
- Annie found out her boyfriend was not only married, but was a Mormon with six wives. She poured arsenic in his drink that night.
- Velma walked in on her husband doing the "spread eagle" with her sister Veronica. She killed them both.
- Mona found out her boyfriend's long walks at night were really an excuse to visit his other girlfriends and a boyfriend. He didn't live much longer after that.
- The extended version of Garth Brooks's "The Thunder Rolls" (though the video depicts the husband as being abusive as well as adulterous):
She runs back down the hallwayAnd through the bedroom doorShe reaches for the pistolKept in her dresser drawerTells the lady in the mirrorHe won't do this again'Cause tonight will be the last timeShe'll wonder where he's been!
- The first published version of the Murder Ballad "Frankie and Johnny" ("He was her man/But he done her wrong") appeared in 1904.
- Before that there was Brünhild(e) in Norse mythology and in Richard Wagner's The Ring of the Nibelung, although in this case Siegfried's potion-induced cheating was combined with him forcing her to marry Gunther. And depending on the version of the myth (though not in the opera), he also raped her to take away her virgin superpowers.
- Lil Kim has killed at least 2 boyfriends in her songs.
- Anna Russell's songs "Dripping With Gore" and "Two Time Man" are (mild) parodies of this trope as used in country music.
- "If You Hadn't, But You Did" from the musical revue Two on the Aisle has a verse beginning in soap-opera-style bathos and ending with a gunshot. It then turns into an angry List Song running down the reasons for saying goodbye to her husband, most of them having names like Geraldine and Kate.
- In the folk song "William Taylor", Taylor is pressed into the navy, so his girlfriend dresses as a man to follow him to sea. When she finds him, she learns that he's taken up with another woman, and shoots them both.
- It's heavily implied in Carrie Underwood's "Two Black Cadillacs", and made explicit in the music video, that a wife and mistress conspired to murder the philandering husband, by cornering him in an alley and running him down with one of the eponymous Cadillacs. On top of that, the video has the car used in the murder exhibit an eerie sentience, such as driving the two women away from the funeral, with them in the back seat, and immediately repairing the damage to itself caused in the crash, effectively erasing any evidence of foul play.
They decided then he’d never get away with doing this to themTwo black Cadillacs waiting for the right time, the right time...
- In Pomplamoose's "Bust Your Kneecaps", a girl has been dumped by her boyfriend and she's giving him one last chance to take her back, with deadly consequences if he doesn't. However, it won't be her doing the killing, but her family, who has ties to the Mafia.
Johnny, there's still time
Together I know, we'd go so far
I'll tell Uncle Rocko
To call off the guys with the crowbars...
- In the music video for Melanie Martinez's "Sippy Cup", Cry Baby's mother catches her husband and his mistress together in the middle of the night and stabs them to death. When Cry Baby walks in on the murder scene, her mother presses a chloroform-soaked rag over her mouth and nose to knock her out so she won't remember.
- Greek Mythology: A subversion occurred when it happened by accident to Heracles - Deianara thought the clothing dipped in Nessus's blood would win her back his love, but it ended up killing him instead.
- The School Days media series of games, anime and manga have this going on in some of the bad endings, when it's not Murder the Hypotenuse. The most infamous examples involve Makoto being stabbed by Sekai (in both the anime and one of the original game's bad endings), but it also includes Yuuki being beaten to death by Kotonoha in Cross Days.
- In Fallout: New Vegas when entering the Silver Rush for the first time you see Gloria Van Graff negotiating with an unsatisfied client. She then has one of her Mooks disintegrate a bound and gagged man to prove a point, and cut dialogue reveals he was an ex-lover who cheated on her.
- When entering Tatooine's Dune Sea for the first time in Knights of the Old Republic, you encounter Marlena Venn who brags to you about having tampered with her husband's droids before fleeing the planet. You later encounter her husband Tanis and learn that he slept around behind her back for years, and she retaliated by rigging his droids to explode around him should he move. You can help him out, or leave him for dead (which most of your companions, even the Lawful Good Jedi Bastila recommends).
- In the Blood & Wine expansion of The Witcher 3: Wild Hunt, Geralt meets the Witch of Lynx Crag who seduced a knight that came to ask for her help with a drought eons ago. When he felt guilty about cheating on his fiancee and tried to return to her, the witch indirectly killed him and says to Geralt "Was I to let another woman have a man who belonged to me? Hmph. I could not abide it."
- If Geralt angers the witch then she ends up killing the man who hired him out of spite, showing that you don't even have to be the one who caused the scorn to become a victim.
- In the Hey Arnold! episode "Ghost Bride", Gerald tells the story of a woman named Cynthia Snell whose fiancé stood her up at the altar for her sister (who he married the next day), so she murdered them both in their sleep with an axe and jumped out the window when the police arrived, killing herself.
- Subverted in The Shawshank Redemption: Andy's wife was cheating on him, and he goes to jail for her murder. He's innocent, though.
- Garth Brooks's "Papa Loved Mama" is presented as comedy. This version is sympathetic to both the lonely, cheating mother and the cuckolded, murderous father:
Mama was a looker, lord how she shinedPapa was a good'n, but the jealous kindPapa loved MamaMama loved menMama's in the graveyardPapa's in the pen
- The ambiguous ending of George Jones' "Radio Lover" can be interpreted as this, involving a cuckolded DJ husband who comes home to catch his wife in bed with another man, and then sings the song's chorus, "The last words they ever heard."
- "The Cold, Hard Facts of Life," most famously by Porter Wagoner. Here, the cuckolded husband is a traveling businessman whose frequent trips away drive the wife to cheat. He finally finds out when he comes home unexpectedly, hoping to surprise his wife with wine and a romantic dinner... but at the liquor store, he runs into a man that — unknown to him — is sleeping with his wife. The ending is left clear: the main protagonist stabs his wife and her lover to death, and he's left to rot in a jail cell as he awaits trial.
- "Blood Red and Goin' Down," a No. 1 country hit by Tanya Tucker in 1973. Then a winsome teenager, the lyrics of this murder ballad fit Tucker well as a young pre-teen, forced to tag along with her father, who is bloodthirstily angry at his wife after learning she had slept with another man (the latest in a line, as implied by the lyrics). Eventually, the man finds his wife, in the arms of another man, in a ramshackle tavern and carries out his brutal deed... but not before sending the daughter outside. However, unknown to the father, the girl watches the slaying.
- "She Wore Red Dresses," an album cut and de facto title tune to Dwight Yoakam's 1989 album Buenas Noches from a Lonely Room. Yoakam takes the role of the cuckolded husband, who married a beautiful young woman purely for how sexually enticing she was while wearing red dresses. The lust eventually dies and she walks out on him; betrayed, the angered husband stalks his wife, tracking her down to a lonely hotel, where he finds her asleep in the arms of her lover. After summoning his courage and bitterly cursing his wife, he walks in, holds the gun to his wife's head... and fires before she knows what's going on. "She wore red dresses/but now she lay dead."
- Ambiguously implied in "Laura (What's He Got That I Ain't Got)," a No. 1 country hit by one-hit wonder Leon Ashley in 1967 (and re-recorded many times, including by Kenny Rogers). The ambiguity comes at the end of the song's second verse, where the cuckolded husband — having snapped for not knowing why his wife has been unfaithful or what qualities her lover has that he might not — takes a gun and demands an immediate answer, "if there's time before I pull this trigger."
- The rap song "Scandalous Hoes II", which ends with murdering the woman for cheating, presented as completely justified
- Possibly subverted in The Darkest of the Hillside Thickets' "Jimmy the Squid". Jimmy is accused of killing his mate for sleeping with another squid. He says he's innocent.
- Tom Jones' "Delilah".
- "Hey Joe", recorded by a number of artists.
- Willie Nelson's "Red Headed Stranger".
- Warren Zevon's "A Bullet For Ramona".
- Weirdly appears on Rome when Vorenus finds out his grandson is in fact his wife Niobe's son by another man. According to Roman custom at the time it was not only Vorenus' right to kill her for her infidelity, but it was also what honor demanded (and Vorenus is constantly shown to put Honor Before Reason). He grabs a knife but doesn't seem like he will be able to actually kill her, so she flings herself off a balcony and takes her own life as a final act of love.
- In Oscar Wilde's "Ballad of Reading Gaol," this is the condemned prisoner's crime.
He did not wear his scarlet coat,
For blood and wine are red,
And blood and wine were on his hands
When they found him with the dead,
The poor dead woman whom he loved
And murdered in her bed.
- The third verse of Dr. Dre and Eminem's "Guilty Conscience" has the two arguing as a man's conscience on whether or not to kill his cheating wife and her lover (Dre tries to talk him out of it, but Slim Shady is goading him to go ahead). They both agree to do it after Slim calls Dre out on his own past ("You gonna take advice from somebody who slapped Dee Barnes?").
- Appears to be the case in Nick Cave & the Bad Seeds "We Came Along This Road". The song's lyrics start with "I left by the back door, with my wife's lover's smoking gun" and then describe the protagonist going on the run.
- Richard Marx, "Hazard", maybe. The male character's accused of it, but the truth is intentionally ambiguous.
- Played with in "The Night The Lights Went Out In Georgia" (a No. 1 pop hit by Vicki Lawrence and famously covered by Reba McEntire). A man finds out that his wife's been the town bicycle while he's been gone, and goes to kill her and his friend who she was last cheating on him with. He gets arrested for it, and as the title suggests, gets the death penalty. Subversion: the husband didn't do it. His little sister got to the cheating wife and the friend first.
- The end of the video for "Down Low" from R. Kelly featuring Ron Isley as Mr. Biggs. After the latter walks in on his wife cheating on him with the former, who was told to keep her company in Biggs' absence but not touch her, he has the former beaten by his bodyguards and left in the desert. Biggs' wife is found in intensive care, having also been beaten for her infidelity, by a wheelchair bound R. Kelly, who witnesses her succumb to her injuries.
- "E," a piece of Country Music by Matt Mason, is a case where it's clearly unjustified being a variation on the folk song "Matty Groves": the husband (the singer) finds his wife ("you") in bed with her lover, and, instead of just killing them, decides to give them a fighting chance, giving them a car, a gun, and a short chance to run before he comes after them.
- Threatened in the song "Ruby, Don't Take Your Love To Town" but the point of the song is that the male character is paralysed, thus why he thinks she's leaving him, and why he can't carry out the threat of "if I could, I'd get my gun and put her in the ground"
- Played for laughs in one of the in-game books in Daggerfall. A Dark Elf man returns home to find his wife cheating on him and murders her in a rage. When questioned at his trial why he murdered his wife instead of her lover, he replies "I thought it better to kill one woman than to kill a different man every night".
- In Adam's Rib, a wife shoots her husband after finding another woman in his arms, but he survives. Her defense attorney, Amanda Bonner, gets the jury to excuse her actions under the Double Standard grounds that a man shooting at an unfaithful wife would not be judged so harshly. Keep in mind that this movie was made in 1949.
- In Oz: The Great and Powerful, Theodora brings down Oz's hot-air balloon down in flames. He wasn't on it.
- In Dragon Bones, Bastilla tries to get a man killed simply for rejecting her and then being vaguely interested in some other woman. More precisely, she puts a spell on Penrod, so that he stabs Ward in the back, after Ward dared to reject her and smile at Tisala. Penrod is then killed by Tosten, in order to save Ward. Maybe she had planned for Penrod's death, as she still needs Ward, and killing Penrod in this way causes him severe emotional pain. She's a villain, and not exactly well-adjusted, mentally.
- Played with in a Star Trek: The Next Generation episode where the plot goes both ways - a male character sees himself cheated on, murders both parties, and commits suicide, then a female character goes through the exact same scenario and reacts the same way. In actuality, both characters were being caught up in the psychic playback of events that happened to someone else in the past. And that someone else was not presented as justified, but as disturbed.