There's a lot of girls out there, do you really want to waste your time chasing one with a boyfriend? I'm not saying don't try to screw her brains out, but she obviously likes jerks and I think you're basically being her nice gay friend. Girls don't want to be fucked by the nice gay friend. Personally I'd make a move, if she doesn't go for it forget about her totally ignore her. Also age doesn't mean anything so forget about it.