Need your input! am i thinking too much like a guy?

Why is that while i had promiscuous relationships i can accept my girlfriend having done that and i get so angry over that? What to do? I cant stand the thought another guy had his way with the woman i love! I think she was used and guys that.... U know what have something over me! I have no problem with my confedence in the contrary i am overly confedent thats why i cant "accept" that another guy had my girl!