How can I stop being jealous. I am aware of my selfishness but I can't seem to put theses feelings to an end.

Ok, I have two female bestfriends that I simply love. I also have one male bestfriend. I used to chill and hang out with them separately but we all went out together once and suddenly "us girls" became all 4 of us and "me and him" became a group. Sometimes, they even hang out without me, or go places and talk and I am left out. I know it being territorial but I can not help it. I feel like the "girls" stole my friendship with my guy friend. Is it wrong to want to have separate friends? Wrong to want things back to the old ways? I would love to be able to hang out together as a whole and not be upset. Or even to allow them to go places and not feel jealous and left out. Any advice? also I do not care for negativity, so if you feel the need, no need to reply.