from A to Z - After
Of the various potential and actual romantic relationships i've had in my life (which total eight), i feel fortunate to be very close friends with five of them.
i think that what it comes down to is that after that period of mourning and loss and potential triggers for "the way things used to be" (however long that period is which varies from person to person), the negatives of the relationship dissipate and what remains is everything that made the relationship great. Then all it takes is a mental adjustment to enhance and appreciate how that relationship can translate to friendship and a nostalgic sense of the past rather than a wistful one, and given my general characteristic of never looking back, not having any regret, that's hardly ever a problem.
of course i have moments of relapse and "what if", but those are fleeting. It's easy to look at this ex-gf who is now happily married and wonder what it would be like if it were me, but i know that if i *had* gotten married at that time i wouldn't be the me that I am, and i'd likely be wondering what it would be like if i weren't married.
of the remaining ex-gfs that i am not close friends with, i'd gladly be if they were willing, but one decided to leave me behind because we developed into different enough people that she didn't feel she could relate to me anymore, another is unlikely to contact me again at this point because she's more of the "putting the past behind her" type (i think), and the third is just flaky on me for reasons that don't matter much any more.
but that's okay. because if after eight meaningful relationships or almost relationships i can still make over half of them still meaningful in a different context, i think that still counts as a win.