In my opinion, I think first and foremost you should realize you are simply dating this girl. You are young and have to know that although you love her, you most likely will not be with her for the rest of your life. If I was you, I would enjoy the time you have with her. When I say that, I mean enoy it to the fullest extent. You may never again have a chance to be with a girl who enjoys other girls. This is a fantasy for most men. It sounds like you enjoy the idea of it, but to be concerned she might enjoy it more than you is just silly. So what if she does. At least you were part of it. :)