Nice Job Breaking It, Rivals

Two characters are fighting over something and in the process the thing they are fighting over gets broken, damaged, or destroyed. Often overlaps with Nice Job Breaking It Hero. May be seen as poetic justice. Usually implies a moral about how fighting is bad.

Anime and Manga

 * In the original Magical Girl Lyrical Nanoha, when Nanoha and Fate fight over one of the Jewel Seeds, they accidentally activate it, almost causing an explosion. Fate then risks her life to contain it and therefore ends up claiming it.

Fan Fiction

 * In the Death Note AU My Stupid Reality Mello and Matt get into a fight over who is the bigger screw-up when they lose Light Yagami's trail that results in both of them accidentally destroying all of the data L had accumulated on Light. Subverted in that L already had the data committed to memory and when he finds out about this he is able to use it as the excuse he needs to justify his continued pursuit of Light to Watari.

Film

 * In the movie The War, two groups of kids fight a battle over a treehouse. The treehouse is pretty much wrecked in the fighting.
 * This is how the Ring is destroyed in the Lord of the Rings movie (though not the book). After Gollum wrests the ring from Frodo, Frodo tries to take it back. The result is that the ring falls into the fire.

Literature

 * Inverted in a short story from Tales of Ravenloft. A young bride's sorcerer husband fights another wizard. Each begs for her help, warning her that the other is evil and intends to destroy her using a cursed portal she's discovered. Repelled by how each cares more about beating the other than about her, she uses the portal herself to kill both men, becoming a nastier villain than either.

Live Action TV
"Joey: As he takes a fork from his pocket, "What are we having?""
 * A particularly tragic example happens in the first season of Heroes. Peter and Isaac get into a fight that is at least partly over a girl they both like. Guess who gets shot.
 * In the I Carly episode "iPie", Freddy and Sam are trying to hack into a dead guy's computer for a pie recipe. It's a slow computer, and Sam tries to take over. They fight over the keyboard and end up knocking the CPU over and smashing it... which turns out to be OK, because.
 * Star Trek the Original Series episode "Requiem for Methuselah". Flint created the Robot Girl Rayna Kapec to be a companion for him. He guided her and James T. Kirk into falling in love with each other to awaken her emotions, then planned to take over. He and Kirk end up in a fight over her, and during the fight she is so stressed out over having to choose between them that she malfunctions and dies.
 * Yeralash has an episode where two boys are laying out presents for girls in their class. They take a large, beautiful doll out of the box, and start arguing which girl should receive that. In the end, they tear the doll in half... and then finally agree which girl should get it now.
 * Friends: Chandler and Rachel fight over a gourmet cheesecake accidentally delivered to them (it was meant for a neighbor who was away on a trip). It ends up being knocked on the floor as they both gaze at it, heartbroken. Later, Joey nonchalantly joins them in eating it off the floor.

Newspaper Comics

 * In a Peanuts strip, Lucy fights with "Royanne", the girl who claimed to be Roy Hobbs' great-granddaughter, over a baseball bat. Snoopy solves the dispute by sawing the bat in half.

Puppet Shows

 * A Sesame Street sketch involves the Two-Headed Monster building a two-headed snowman. Only one carrot is available, so the two heads argue over the carrot. The carrot snaps in two, so each head of the snowman can have a carrot nose.

Web Original

 * Occurs in Doctor Horribles Sing Along Blog: Two men battle over a girl,

Western Animation

 * The Simpsons: Bart, Milhouse & Martin go in on buying the first issue of Radioactive Man for $100 and end up destroying it during their squabble.
 * TMNT Back to the Sewer: Raph and Mikey manage to rip the Green Mantle in half while fighting over it, splitting its power between the pieces.

Real Life

 * Needless to say, it happens in real life all the time - from kids fighting over a toy and breaking it to governments fighting over a province and reducing it to a wasteland.