Suggest me a book about a relationship that doesn’t work out and the character learns to move on

I’m looking for a book where the main character is in a relationship that slowly falls apart or just doesn’t work anymore, and the story focuses more on how they process the breakup and move on with their life.

I’m not really looking for a typical romance where the breakup just leads to a new love interest right away. What I’m more interested in is a story that explores the emotional side of it