...and I'm wondering what sort of responses are acceptable in a situation as this?

That is, my current boyfriend went with a girl for a while who is pretty much perfect in every way. Then they broke up, but apparently nobody knows why. He dodge the question when i asked him. Someone implied it may be because she had to go away for school, and even though she comes home for vacations, weekends, and it isn't very far away at all, he did not want a long distance relationship. But he did not give me an answer when I asked "Why did you break up with her?"

So now they are still good friends, except that she still likes him very much. This puts me in a poor spot. I try my hardest to not be jealous of people anymore. I used to be a pretty jealous 'partner',and i realised, so in this relationship, I am trying my hardest to change that. But it's really difficult to guage what behaviour is appropriate when I have always just been so jealous. I feel left out and get upset sometimes when we hang out with her, and I listen to them talk about the fun they used to have. She is nice and I like her on her own, but when I have to hang out with both of them, things are frustrating for me. I don't tell anybody or show that I'm upset, but it is bothersome. They still even kind of flirt(i.e., tickling each other, he 'scares' her by sneaking up behind and grabbing her). Is it unreasonable of me to feel upset? I asked him if he still liked her and he seemed real uncomfortable with that question. I mean, he said no, but was laughing nervously about it...

Any advice about this situation is much appreciated...Advice on acceptable behaviour, ways to manage jealousy, 'easy' ways of approaching the sitauation or how to discuss it with him. I think talking of serious subjects like this is what makes him nervous, so I try to resolve my own issues by myself, so as to not bother him. I wouldnt ever want to become between their friendship, but I want to stop wondering constantly whether or not he still likes her or not. Tired of being the second-place in relationships. =P