Why do all my gf's friends hate me?

Everytime I'm with my girl and they're around too I seem to spark some sort of drama. I'm a pretty nice guy and probably one of the best boyfriends that I have ever known. What cause these women to be such raging hormonal bitches? It is my hypothesis that since they are immature, for the most part, they are extremely jealous that my girlfriend loves me more than Them and they Enact their revenge on me.