Another thought: actually, NYCindie, I don't know any monogamous people who maintain contact with old lovers/exes.
In fact, most people I know think an ex is someone who should not be in your life at all. And that even if you had a good relationship with someone, it's "your past" and moving on means having no contact whatsoever. Part of what has drawn me to polyamory is that I find that attitude totally bizarre.
By coincidence, I was just about to post a question / discussion about this very issue, which I will do...
Single, straight, female, solo, non-monogamous.