No One Has The Answer...Yet.

Why is it that one cannot treat one's girlfriend as a best friend too? Why is it that when it comes to girlfriend, one becomes possessive. It's like if your friends were to hang out with their other friends once in awhile, it doesn't matter. But when it's your girlfriend who's going to hang out with her own friends once in awhile, you get possessive and annoyed. Sometimes even jealous.

Why is that so? What is specially special about the girlfriend that makes you feel that way?