I don't want my roommate to have his girlfriend/friends stay over frequently, do you know about this yet?
Is there a reason in particular why you do not want his gf and friends over?
They are totally unnecessary around me. I don't care about them
Try to put your roommates needs into consideration as well. Maybe you guys can make some sort of compromise that would be helpful.
I don't really care about that, she is so annoying and useless.
People have friends and they need to be around them. Just bear with them and try to tolerate their presence. Join in them once in awhile and maybe you can be friends with them too.