Wait, how is a guy gay if he has a girlfriend? Even if he is a wimp, that means he's bisexual at the extreme.
Also, even if he isn't quite the way you want him to be, it's not your job to ostracize him and ridicule him until something happens. Even though it is pathetic that his girlfriend is going to fistfight instead of him, I didn't see any suggestion stating he should fight instead.
Never hit a chick, even if the chick looks like a dude.
Really though, I'd go apologize to the kid. If you have too much testosterone to do that, than just refrain from being a jerk. Plus, if he's emo, he wants attention. If you don't give him any attention, his emo nature won't be quite as offensive.