There are two kinds of people in the world*: people who can be friends with people they have dated (or been married to), and those who cannot. I am generally one of the former. I don't say this with any particular pride, since I'm sure it springs from some sort of desperate need for external approval and emotional fulfillment. It can also be a tremendous pain in the ass.
For those of you in the second group who have never tried it, the biggest problem in the long term often turns out to be new lovers and spouses and such who believe that communicating with people you have had intimates with is practically cheating, and if not cheating then it's certainly uncomfortable and not something to be tolerated. So what happens is that you are friends for a while, then one party or the other drops off the face of the Earth. They resurface when the relationship is over, or presumably if it "takes" then you never hear from them again.
I'm not claiming that there is never a reason for people to feel threatened by old flames. After all, they call them that for a reason. There are almost always unresolved feelings that linger after a serious relationship, and they are rarely tidy. I have suspected on more than one occasion that the jealous new lover or spouse provided a somewhat welcome excuse to pack all of that emotional baggage into a Samsonite "Suppressor" hardside with wheels and retractable handle, lock the lock, eat the key and stuff the bag into the depths of the subconscious, where it will often keep the door from closing properly.
And I can see where children could motivate one to cut ties with the past. "Kids, this is the man that gave Mommie the best orgasms of her life until he dumped her for that slut and she settled for your Dad", is not a conversation most parents (or children) probably want to have. As much as I believe in being honest with children, there are just some things no one should have to hear before they are about thirty. Like the night I heard my mother scream from all the way upstairs, and I don't think she stubbed her toe on the dresser.
I lived in Texas about 30 years ago and dated a girl who waited tables at a restaurant I frequented. They made a killer Monte Cristo sandwich. We were very comfortable together. She tracked me down one time after a divorce (don't judge, you know you've done it), discovered that I was in a serious relationship, and we settled down to a period of exchanging Christmas cards and e-mail once or twice a year. After a few years of this she sort of freaked out one day and admitted that she had originally gotten back in touch because she saw me as "one who got away." We worked through all of that and she became a very good friend, though still living far away.
That is until last month when she told me she was getting married to a guy she had kicked to the curb a year or so ago. I had noticed I was hearing from her less often lately, and I expect it will stop altogether in a month or so when they get hitched. That's the second friend I have lost this way in the last year or so.
So why do I bother maintaining relationships with old lovers? Two reasons -- three if you count the emotional neediness thing. First, these people know who I was. There is a lot of mythology and philosophical meandering behind the idea that we change all of our cells every seven years and become totally different people. Scientifically, it turns out to be mostly crap, but as a metaphor the concept is very appealing. We really do become different people as time goes on (if we're learning anything), and the people we know now have no way to know those past selves. Even people we have known a long time have progressed with us, and the old selves are buried under the new. Sometimes it can be very good for us to have someone remind us of the people we came from.
The other benefit is the emotional baggage thing. There can be a lot of discomfort and rehashing of old greivances and nostalgic yearning for a while, but these things will fade. Once we are able to disconnect the expectations and hurt and anger that we attached to the other person, we can rediscover the person we thought was cool enough to sleep with in the first place. Except by that point we also usually have a clear view of why that is not an experience we care to repeat, so the attraction thing tends to fall away. Perhaps the biggest benefit is that each person is left holding the big bag of expectations and hurt and anger, and is forced to either deal with it or drop it. I tend to wear my emotions in places where I can't see them, so it helps to be able to unpack a bag of old crap and get rid of it sometimes.
I definitely have to give the wife props on this subject. I know she doesn't just love the idea of me being in touch with old lovers across the country, but she understands how important it is, and how much it helps my relationship with her, so she grits her teeth and puts on a big smile and very rarely makes a snarky comment. When she does, it's usually both deserved and funny. She's a class act.
* Actually, the two kinds of people are: people who think there are only two kinds of people in the world, and those who know better. Makes a nice kind of koan, doesn't it? I think perhaps it's a quantum thing. There are two kinds of people in an infinite number of worlds? People and anti-people? Or vice-versa? Or maybe each of us is both kinds of people until we are observed being one or the other. Any psycho-physicists out there with an opinion? On a related note, this is why computers aren't very good thinking machines. They believe there are only two kinds of everything.