Well, sorry for this, but when girls say that we have a boyfriend to a guy we meet is usually because we want to let him know that we are interested in being friends with the guy, but nothing more. If she was interested in you as more than a friend she wouldn't tell you now, she may tell you once you are much closer and add that she is not fine with him or something like that. But in this case it seems to be that she wants to be your friend. I'm sorry, but hey! You can be his friend, and who knows? Maybe she has beautiful friends she can introduce you to :b