geez, some people are stupid. Why do you ask if he's talked to her about the problem? Of course he already has. In case you are clueless, most people come to an online forum as a second resort, not a first. I'd imagine he's talked to her several times already since the problem has been going on for a month. I hate when people say "ask her what's wrong" or "tell her how you feel." No shit. That's what anyone would have done first.

Sucks for you ibme. There's nothing you can do except deal with it or break up with her. I say dump her. Trust me, it will save you a lot of grief in the future. Your gf is not being fair if she thinks she doesn't need to satisfy you. If she doesn't want to have sex, fine. Why can't she give you oral instead? Try being emotionally distant with her for a few weeks and see how she reacts. Don't kiss. Don't cuddle. Don't take her out. Don't call her as much. I guarantee you she will throw a hissy fit. Stupid girls.