Hey, hon I've been the girl you are worried about in this situation, and I can tell you that she probably feels like ***** that she's not allowed to be friends with this guy because it upsets you, and that she probably can't understand why you're being like this because she doesn't wanna steal him just be mates. I'm not guaranteeing she's innocent, just saying that there is every chance she is totally puzzled by your (sorry, but it is) unreasonable behaviour. I think you need to back off from this, however hard it is, but all I can suggest to help you with that is talk to her yourself? Maybe if you were better friends with her yourself you'd see she's not so bad and you'd feel less threatened by your boyfriend's friendship with her. Also, this isnt meant to be offensive so im sorry if it is, but if you feel this jealous is the problem perhaps that you don't trust your boyfriend enough?? Maybe this is a problem you need to work through with his irrespective of the girl?