Should I find a new group of friends?

I've been friends with this guy since I was 13. Well, he's kinda feminine and he's also biual (and dating a guy). Don't get me wrong, he is my BEST friend and I love him like a brother. And I don't really care that he's feminine or bi. To me, guys come in many different breeds. He actually helped me get more in touch with my feminine side, which is pretty awesome! He's also an all-around nice guy. And his boyfriend is an awesome guy too and they actually make a cute couple (lol). However, whenever we hang out with our other friends, who are super masculine, they get uncomfortable around him. Whenever he steps out of the room, they insult him and I always have to defend him. I don't see anything wrong with him so I don't know why they can't just stop it. If they're that insecure about their own uality that they have to go after a guy who's feminine, then that's pretty sad.... And one time, as a VERY cruel prank, they bought him girls' clothes for his birthday... He stills hangs out with them and pretended to not be bothered but I can tell he hates them for this cr*p they put him through. Should I just stop hanging out with them and tell him to do the same? We can always find better friends....