Maybe one of the parents died, and the kids are afraid of them being forgotten. Maybe they got divorced, or are in the process of it, and the kids want them back together. Maybe there are reasons that are completely unrelated to the family dynamic. Whatever the reason, the children are not happy with the idea of their newly-single parent moving on with someone else. For some kids, there's only one solution—sabotage any relationships their parents might try to have.
The kids come up with elaborate schemes to scare away any potential suitor for their single parent, and Hilarity Ensues. If the suitor has the warning signs of a Child Hater or Wicked Stepmother, this trope can be justified. If the suitor they're trying to chase away is actually a nice person, the kids will usually see the error of their ways and accept the suitor into their lives. Count on at least one speech where the parent in question tries to assure the kids that just because they're seeing someone new doesn't mean they love them any less.
This trope is the opposite of Kids Play Matchmaker, where the children are trying to create romance for their parents instead of destroy it. The two can overlap if the child is chasing away a romantic candidate specifically so their parent can be with the approved choice of their children.
Can also apply to older siblings or other relatives, though it's usually parents who are at risk of having their dates ruined.
- Are We There Yet?: Lindsay and Kevin are certain their father will come home to reconcile with their mother, so they spend half the movie tormenting her potential suitor, Nick, to scare him away. They go so far as to pretend that he's kidnapped them, and even hop a train to get to their dad's house. When they arrive, however, they find out their father has been lying to cut them out of his life, and he's started a new family without them. Despite all their cruelty towards Nick, it's hard not to feel bad for them when you see their faces.
- Baby Boot Camp: Charlotte tries to make Julia look like a bad nanny by hiding her baby sister to make it look like Julia lost her, so she'll get fired and stay away from Charlotte's father, Scott.
- It Takes Two: Amanda helps Alyssa sabotage her father's gold-digging fiancée, Clarissa, and push him closer to Amanda's motherly social-worker.
- Nanny McPhee: The Brown children sabotage their father's tea party date with Mrs. Quickly by putting a toad in the teapot, trying to dump Jell-O on her, and throwing mashed potatoes at her. While she doesn't realize their tricks, the father's various attempts to rescue her make her believe that he is a cad who wants her to be a casual fling rather than a wife.
- In both versions of The Parent Trap, before they can reconcile their divorced parents, the twins must first get rid of their father's gold-digging fiancée.
- Problem Child 2: Junior ruins all his adoptive father's dates with stunts like phoning the woman's jealous ex, and rewiring the doorbell to electrocute people. Of course, it's no wonder Ben didn't believe him about LaWanda being a Child Hater with plans to send him Off to Boarding School. Sucks for Junior.
- The 2005 reimagining of Yours, Mine, and Ours has the kids of a blended family playing this after their respective parents get married. The father is a no-nonsense Navy Seal who acts more like a drill sergeant than a father to his kids, and the mother is a free-spirited artist who likes to let her kids run wild. After the wedding, the kids from both sides clash horribly, both with their stepparents and each other, and scheme to break up the marriage so they can go back to how they used to be.
- Charmed (1998): After Piper and Leo separate their son, Wyatt, starts scaring away the men Piper tries to date by using his powers to make his eyes glow in front of them. Piper eventually catches on when he does it to Paige's Love Interest as well.
- Hannah Montana: After seeing their father on a date at the movies, Miley and Jackson go undercover to her office to dig up some dirt on his new woman.
- Jessie: A non-parental example; The Ross kids try to break up Brooks and Jessie's engagement when a job offer for Brooks in Africa means she will have to quit as their nanny after the wedding.
- M*A*S*H: The B-plot of an episode involves Radar discovering his widowed mother has begun dating again. He voices his disapproval of this to Hawkeye, who figures out Walter's real discomfort stems from not wanting to share his mother after so long. The doctor proceeds to relate how, after his own mother passed away during his childhood, his father began dating another woman. Hawkeye made it a point to showcase his own disapproval by being cold and unwelcoming to the woman until the elder Pierce broke off the relationship. While satisfied at the time, the older Hawkeye realizes, much to his dismay, that this was also the last time his father ever dated, and he's now alone and elderly, all because of his son's selfish refusal to let him move on.
- One Day at a Time (1975): Julie and Barbara try to get their parents back together after their father announces he's getting remarried. Even after the plan falls through, later episodes show they still resent Vicki and see her as an obstacle to their parents reuniting.
- The Suite Life of Zack & Cody: Zack is excited at the news of their mom's uber-wealthy new boyfriend proposing, but Cody prefers life just the way it is, so he tries to halt the proposal by stealing the ring.
- The Amazing World of Gumball: Happens twice with Richard, who in all fairness has the maturity and emotional stability of a kindergartner, and his mom's boyfriend, Louie.
- The first episode where Louie is introduced as Granny JoJo's boyfriend, Richard tries to break up their romance, first by preventing her from sneaking out on a date, then by out-manning him at a Man-Off to give himself more authority. In the end, he accepts that his mom needs to move on after his dad left them.
- In a later episode, Richard gets Aesop Amnesia when Louie and JoJo announce they're getting married. He actually tricks Louie into signing adoption papers, adopting Louie as his son and then forbidding him to marry JoJo. Louie retaliates by tricking Nicole into signing adoption papers, adopting HER as his daughter, and then forbidding her to see Richard. The family ends up tracking down Richard's Disappeared Dad, Frankie, in order to sort out the mess.
- American Dad!: Stan takes this trope to the extreme by kidnapping all his mom's dates and leaving them to rot on a deserted island. Keep in mind, he started doing this when he was still a little kid who played with action figures.
- Bob's Burgers: The kids find out their aunt Gayle is dating Mr. Frond, the annoying guidance counsellor from their school. They realise if the two stay together, Mr. Frond would become their uncle and they'd have to see more of him than they'd like. Tina sings a song about relationships in "Spanish" that is actually comprised of mundane phrases she knows of, while Louise translates. Louise convinces Gayle (who thinks the song is more meaningful because it's in Spanish) that maybe she and Mr. Frond won't be a good match. The kids also find a stuffed doll in Mr. Frond's bag that is modelled on Gayle. They know if he gives it to her, she will become committed to the relationship and there's a greater chance of them staying together. They hide the doll, but Louise eventually realises she's being too harsh on her aunt and decides to let Mr. Frond give her the doll.
- The Casagrandes:
- In "Teachers Fret", Ronnie Anne tries to sabotage her father's new relationship with her teacher to avoid embarrassment.
- She and Bobby also sabotage their mothers date in "Date With Destiny" when their grandmothers favorite celebrity psychic predicts "a lifetime of happiness" for the moms sign if she is "back with her ex" by that evening.
- In Rugrats in Paris, Chuckie wants a new mother to replace his dead one Melinda, but unfortunately, his dad Chas is dating a mean woman named Coco. When Chas and Coco are about to get married, Chuckie shouts a Big "NO!", which is his first word that isn't in Baby Language. Chas instantly calls off the wedding.
- The Simpsons: Funny enough, Milhouse actually tries to do this with his divorced parents when they start to reconnect. He likes how they spoil him to compete with each other.
- SpongeBob SquarePants: Pearl is deliberately rude and obnoxious to her dad's new girlfriend Cashina, who is a living breathing wad of cash, to avoid getting a Wicked Stepmother like in the movies. However, Cashina wins her over with girl talk. Sadly, Cashina turns out to be Plankton in disguise.