I understand that situation all too well. Ex's become friends, or were friends from the beginning, and for some people, too much to give up. I've stood in that shoe, before, and realized how much it was hurting the one I was with. Its a touchy subject, but if you are into someone enough, you should be willing to do anything for that person (including giving someone up), but on the other hand, if you are into someone enough, you should not want the person to give anyone up for you, as much as you may want to.