I look at it that our lives moved on in general in all cases and for a reason. Most of my exes are married now, most of them are on my Facebook and I felt nothing but happy for them getting married, the past is the past.
The last one is maybe the one that isn't so clearcut but there are reasons for that and i'ts not that I would change things if I had the chance, definitely not! Strange really, I saw his now wife earlier and it got me pondering a few things...mainly being glad I'm not with him anymore. I think more unresolved issues.