I'm sure that some of them do. However, girls typically approach the encounter with a different set of expectations than do boys, and have different emotional effects afterwards.
I mean, how often do you hear of a poor young boy being pressured into sex by his girlfriend, versus the other way around? How many men do you know of who felt disappointment or shame after their first sexual encounter?
That's not to say these things never happen, but it is MUCH less frequent among men. And on those rare instances when a boy is reluctant to have sex, or feels disappointment after sex, it is almost always because of religious belief and not for any emotional reasons.
Boys and girls are different, and that difference is magnified when it comes to sex.
Well, I did, but I was alone, so nobody knew about it.
I agree with your point. When I was a teenager, I had affairs with a couple of different women in their mid-twenties. They both knew about birth control and what they were doing. I was just a dumb kid having a good time, and knew there wasn't going to be a long-term relationship. Each of them had just gotten divorced and looking back, I think they were trying to relive their high school experience as "queen of the prom." They went on to guys their own age and I kept my mouth shut, because it was just as illegal then as it is now.
I had a cousin that fell in love with one of her high school teachers, and it was an entirely different situation. I have no idea how far the relationship went, but her parents sent her to our house for a while. She thought she was going to marry him, and I think it affected her the rest of her life. It just affects girls differently.