Innately selfish?

Was discussing with my friend on the way to school about friendship and BGR. Somehow both of us just agreed that friendship is purer than BGR.

When people get into BGR, they become more selfish. Or is it that BGR is, by nature, a selfish business? When two persons get into a BGR, are they agreeing and announcing that I am yours and you are mine? In that case, BGR IS a selfish business.
No wonder people hate to go into BGR with good friend, afraid that their frienship may turn sour, or they may lose this frienship if the BGR does not turn out well. If BGR does not work out well, it shows that one party, or both, has seen through and through the person. Then he should not feel a sense of loss to lose her after the BGR has ended.

Why then, do people still lament for this kind of loss? Is it because they miss the person as the person before the BGR? Why is it that chemical change to the relationship between good friends do occur once they enter BGR? What is so great about BGR? What do people have to change when they enter BGR? Why do they have to change?

Don't feel like finding an answer. Just coming up with lots and lots of wu liao questions to fill up this entry.