Girls and boys

Why is it that when a boy and girl meet each other in kindergarten they are thinking to each other "Jerk...Cretin...Imbecile...Primitive lifeforce..." But then the same girl and boy are in high school snogging each other within an inch of each others lives without any intention of stopping? That is just sick and wrong. If your going to have an enemy, make sure that it is for life or at least make a peace offering to show that you forgive them of their wicked ways before you go to different schools and become "reunited" and when you see your photos from kindergarten you don't have to say something along the lines of "So you were the one who put the Elmer's glue down my butt. And I still have problems when I try to crap in the bathroom.