Well, if you really like her, accept the challenge. Be your best self. Be bigger than him, nicer than him, smarter than him, more stable than him, go to a hair stylist and ask your friends how to dress, learn more about music, and about the scene, but by all means be yourself. If she goes for the other guy, then she's going for some short term fun, living a fantasy that's pretty understandable for young person (in fact, I think that's why you're with her, not someone more grounded). If the effort of trying isn't worth it, then end the relationship with her, but do it with civility because that's who you are.