In the anime world, it is very common for at least one of the main characters to have an implied love interest, one example being Demon Slayer's Zenitsu having an overzealous crush on Tanjiro's sister, Nezuko. Often, fans hope that the two will end up together or at least see some flirting between them. Most of the time, these characters do get together canonically. However, being in a relationship does not necessarily guarantee they will last until the end, and some have even broke up during the middle of the anime.
On the contrary, breakups do not always have to be disastrous, and the characters might even mutually decide on splitting up. Not every anime couple is meant to be, but there is always the choice for them to stay friends.
Sailor Moon: Mamoru's Will to Protect Usagi
Although they did not get along well during the majority of the original Sailor Moon anime's first season, star-crossed Usagi and Mamoru eventually fell in love after recalling their past lives and realized they were destined to be together. However, this is cut short when Mamoru starts to have what is later revealed to be false visions of Usagi meeting her doom.
Not wanting her to get hurt, he decides to break up with her in hopes to prevent this ominous future. While Usagi is naturally upset by this, she didn't let it get her down, and continued to perform her duties as a Sailor Guardian. Thankfully, she and Mamoru were able to reconcile later on.
Dragon Ball Z: Bulma and Yamcha Were a Classic Example of Toxicity
Fans who remember Dragon Ball Z can't forget the power couple that is Bulma and Vegeta. However, they were not always together, with Bulma's first partner being the nervous Yamcha. Given Yamcha's desire to get married despite his shyness around women, and Bulma being a free spirit that wished to see the world, their clashing personalities would eventually lead their romance to its end.
While Yamcha was initially jealous of Bulma's relationship with Vegeta, he chose to support them and their son Trunks, becoming a good friend to the family.
Naruto: Sakura and Sasuke's Relationship Was Mostly One-Sided
The long-running classic, Naruto, is no exception in showcasing destructive relationships. Sakura has shown her admiration and romantic interest in Sasuke from the very beginning. She even went so far as to ditch her best friend and do whatever she thought he liked, believing he would eventually return her feelings. Wishing to grow stronger, Sasuke left Sakura behind to train with Orochimaru, despite her pleas for him to stay with her.
Although she was unmistakeably heartbroken, Sakura's feelings for Sasuke remained unchanged, and she was fine with taking things easy with him for the time being. It wasn't until Sasuke returned from a war that the two were able to strengthen their friendship, causing him to finally love her back.