Hm. These are damn good questions, so thank you for forcing me to think about this haha.
I personally like to let my relationship flow, as well as the problems in it. Once in a while it’s good and healthy to have a serious conversation with your partner about the problems that you’re encountering from time to time. However, if that becomes a habit, and you find yourself getting… hm, kinda hungry for problems, then you’ve got an issue.
My advice for you is to talk about solving problems with your partner before you even start a serious relationship - simply make a “deal”. When you see that a specific situation might be a problem and might affect your relationship - talk to your partner about it, “look into” the possible problem, and solve it immediately. That way this problem won’t occur again.
But. If you don’t accept the possible presence of the problem and keep it to yourself - you’ll explode. You’ll become manipulative, envious, paranoid and so on. And it’s hard to cut down the root of a tree when it’s already enormous. Think about it - I think that this is how you should deal with problems in a relationship. My opinion, of course.
Anyway, about the breakup… I don’t even know how and under what circumstances that happens haha. How do you even break up ヾ(´･ ･｀｡)ノ” I think that you shouldn’t break up when you feel like the flame is over, because there’s still a tiny spark, and maybe it’s just temporary; maybe those feelings will restore their force?? I’m not sure because I’ve only had one breakup and it was like 3 years ago and it was dumb, plain and emotionless. So… yeah. You shouldn’t break up unless you’re sure that the power is over, that you don’t want to spend time with that person anymore and that you two don’t get along at all. Everything else is solvable.
And remember: love is like a zipper. When it gets damaged, you can fix it up, but the crack is still there and eventually it will get damaged again. This time, permanently. "Trust is like a mirror. You can fix it if it’s broken… but you can still see the crack in that motherfucking reflection."