Several of my friends girlfriends that they've had have become quite territorial. And I've seen it implied from many comedians that this happens to them too. I also vaguely recall some stories of men being territorial about their girlfriends, so i'm not going to say it is a female only trait.
And by territorial I mean that you distrust your mate hanging around with people of the opposite gender, and/or you feel your mate should want think spending time with you should always take priority over them spending time with anyone else.
So for the people here who have mates(I always use the term mate because i dont want to imply the genders of the pair, and i dislike the term significant other, incase anybody is wondering) and for those of you who wanna guess how you'd behave with a future mate, how territorial are you with them?
I ask this partially because I'm curious, and partially because my friends have expressed that they find this quality extremely annoying(and i would agree with them), and i'm slightly afraid it is universal.