That's probably because there are still some qualities in your ex that attract you. Although there are some wonderful things in your ex, there must be something in him that you don't have and you yearn for very much, so even if you are separated, you will always think of it.

This is actually a kind of contradictory psychology. While I miss him, I refuse his beautiful personality, and sometimes I am quite helpless. So since we broke up, we should let it go. Trapped in the past, I can't start a new life by myself.

Even if you two get back together, you will still repeat the previous mode of getting along, and you will also be hurt, and you will not be any better than before. Let go when it's time to let go.