As per relationship is concerned, the best thing first is to Shed all EGO and put your head down and accept..
Dont go in search of root cause as this may further deter the relationship.. To prevent more harm happening to the relation, say Sorry, go for a drive, dinner etc, and speak try to understand where it went wrong ( leave your ego in the dustbin), who was wrong, even if the other side is wrong, say sorry, and as you iterate, you will see the magic...
Never run from problems, or be speechless for 2-3 days.. that all will tear away the relationship.. be close and it goes on ...

Cheers...