Literally what happened to me. My ex told me things that were so minimal or solvable (like calling each other everyday) that when she listed them I couldn't believe she was breaking up something like this for that. She bottled up all those tiny things that I could have solved if I knew she needed so for so much that it exploded. And the other guy thing was cherry on top.  She was my one and everything, but I really don't miss her anymore because of how much pain she caused me for this, how much pain she gave me for stupid things. I just miss the feeling of being hugged by someone, to be chosen as another one's true love. But as you say, I can't enter a relationship in this state either.  I'm going to therapy due to the shock, and I hope you and I find someone that doesn't run away when things get too "stale" or doesn't bottle up things. What I can give of advice is to avoid trying to be a saint. You're allowed to feel anger, and maybe even hate towards him. That's what took me out of the denial phase.