Former lovers as friends.

Why can't I remain friends with my former lovers? Because! That's why!
Seriously. Of all the women with whom I've had sex, and was in love with, how many do I have an active friendship with? None. It's not that I don't want to. I think it's something that happened after the breakup.
For me, it has not been uncommon that the opportunity for post-breakup sex presents itself. If at that moment I have no prospects, I will seize the opportunity. Sometimes this opportunity presents itself more than once. Still, if I have no prospects, I will seize the opportunity more than once. I think this is where the possibility for a future friendship breaks down. If only I could keep it in my pants. But what do you say to a woman you've been in love with whose telling you to take it out of your pants? How does a guy say no to that? Even now, if I were not involved with anyone and someone I used to be in love with wanted to try and re-kindle the relationship, I would consider it (in most cases). Definitely NOT the woman I was married to or anyone I ever lived with though.
The only way I've been able to say no was if I was becoming involved with someone else. In that case there is an obstruction. A reason for me not to seize the opportunity. When that happened, they felt rejected. Another wrong turn in the post breakup interaction game.
How do people do it? I know lots of people who are really good friends with their former lovers and former spouses. I wish I understood this.
I guess I haven't cultivated this ability partly because my love relationships are very intense. Any current lover I might have probably wouldn't take kindly to me having a close association with someone who had been so intimate with me. One day, maybe I'll get it.