Most Helpful Guy
Sounds like a dude who really hates himself but instead of dealing with his own self loathing he lives his life trying to devalue the world around him to match his own level of pitifulness. The guy just needs some counciling to help him learn to love himself.
Most Helpful Girl
He's an idiot plain and simple. This guy thinks that he's something special because he has a big ego. The only reason he has a girlfriend is likely because the girl thought he was nice at first and is now got a bunch of feelings for him since they have been together a long time.
I really hope she finds the courage to leave him. Any person who thinks it's okay to tell their partner to shut up all the time is not a good partner. People get on our nerves and I get that. But it sounds like this guy is just doing it to be mean to his girlfriend and he knows it. I hope she realizes this sooner rather than later.
I also hope your boyfriend sees how much of a jerk this guy is and stops hanging around with him. I wouldn't want someone like that as my friend.