Good for the Goose. Not good for the Gander?

Because you let them get away with it. People (yes, women included) frequently stake out all the territory they can and then go look for more. Naturally, this is an illusion because all relationships are voluntary. I don't put up with people playing that kind of game (mostly because I'm already married and no one makes presumptive claims over sweetie).

I don't take the behavior as an indication of a good partner and generally show them the door on the first display because they somehow thought it would be ok.

Its a pride thing, their boys always talk about yeah you a bitch if you let a girl run you woop woop. Ya know. So he doesn't want to look like a punk ya know. If you love him tell him hey if I let you act like that in front of you friends you gotta do something for me so it would be fair. Ya know. Or it could be that he knows his friends think you hot and he just trying to keep distance because he don't want to loose you. I would ask him, communicate to him why he does that so you understand, then you guys can come to a conclusion. Work it out from there. But be sincere and nice when you do it, he might get defensive. But the whole thing is there is a problem that you don't like and you gotta talk to him about it or other wise it will remain a problem. Cool?

Because men are always in need to show that they are in control of every aspect of their life. Doesn't matter whether its at work or home. Its a way of getting respect from other men if they see you are in control. Last thing you want is people thinking that you are whipped or that you can let any other man hit on your woman.