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:
- Killing your spouse: The cheater wants a fresh start with the lover, but knows a divorce will take too long and be too costly, especially in light of their adultery. Or the cuckolded spouse discovers the affair and snaps.
- 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 the affair will certainly be found out now. Either way, the cheater gets rid of them for good.
- 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 Til Murder Do Us Part.
- 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 Til Murder Do Us Part if both lovers are involved in the spouse's murder.
- 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 decides 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.
- Killing somebody else: In some cases, other people further outside of the main love triangle become involved. Maybe they kill a relative or someone real 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.
- 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' case, to keep the affair from being discovered.
A sub-trope of Destructive Romance.
- Subverted in the Sin City album "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, who had been hired by the man's wife to track her husband for evidence of the affair.
- This kick 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?
- 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 snubnose 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.
- 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.
- 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.
- 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.
- 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.
- A Perfect Murder: Steven's fist 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. At 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.
- 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.
- 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.
- Played with and subverted in Who Framed Roger Rabbit where the eponymous animated character is framed for committing murder after viewing photos taken of his cartoon wife literally "playing pattycake" with a human man.
- 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 joke:
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.
- 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 Dectective Bree Stone hostage, and is shot by her partner Mueller.
- Francesca and Paolo from The Divine Comedy were two nobles who had an affair that was ended when Francesca's husband killed both of them, sending the two of them to Hell for lust.
- In Salems 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".
- Nicholas Meyer's The Seven-Per-Cent Solution from the Sherlock Holmes chronicles has a case based around this. Holmes is brought to Vienna, Austria to meet budding psychologist Sigmund Freud, in an effort to treat Holmes for a 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.
- "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 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.
- "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.
- 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.
- Diagnosis: Murder: In one episode a woman kills her lover in a fit of rage after learning he's been unfaithful.
- 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.
- 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.
- The programming on the Oxygen almost completely consists of shows such Snapped, Scorned, and Martinis & Murder about murders committed by scorned lovers or the more possessive leg of a love triangle.
- A complicated case in season 3. A girl was sleeping with her step-father, 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 affair 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: 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.
- The documentary series Justice Served: Murderous Affairs 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.
- 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 meet 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.
- 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.
- 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 Encholls 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 discover 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.
- 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.
- 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.
- 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.
- A rich heiress kills her husband and the two women he was having a threesome with.
- The main plot of Pagliacci, when Canio discovers his wife Nedda is having an affair, he kills her and her lover on stage in the middle of a performance. The audience initially thinks Canios declaration that he is no longer Pagliaccio all part of the show but when he stabs Nedda, they realize its real.
- As Far Cry 4 progresses, it's revealed that Ajay's mother had an affair with Big Bad 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.
- 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 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.
- 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.