I am not going to go into an analysis of why, because i have been there and it hasn't been any fun nor have i had any luck figuring it out - the result of which, i guess, is that i tend to avoid any argument. I tend to run away, change direction or find a sad confused face in my huge array of expressions to avoid them whenever possible. But there are times when, well there's no running away - the other person really cares or 'needs' to have the 'conversation'.
Those are the tough ones and every now and then one does sneak through my super tough defenses. And thats when it hurts - because there's an ego and a false sense of self defense that's been breached. I try to protect myself and it hurts even more. But thanks to my exceptionally short term memory, the effects do not last long enough for me to remember to make exactly sure not to get into another argument. And so the cycle of conversations continue until another argument surprises [for lack of a better word] me.