You’re reading a romance novel or one with a major romantic subplot and then the designated love interest of the female (or male) protagonist does something that hurts the protagonist and you hate them for it, and wish they didn’t end up together… but sure, they end up together.
Due to the nature of this discussion, spoilers from the books are included.
Example of how to write:
Gideon de Villiers from The Ruby Red Trilogy.
>!spoiler here!
Krum was 17 and ginny was 13 when they would have been together in the 4th book. Haven’t read them in a while, but I don’t remember too many other opportunities for them to meet up. Was already a creepy enough age difference with Hermione.