She probably does. But hormonally speaking, girls had the same desires in earlier times too. What kept them from going all the way in the back seat? Fear of losing their reputations. Fear of being hurt. Being told that these guys didn't REALLY love you, and then would walk away after you "gave in." Stories about other girls who gave in, and were shamed with either being dropped or called a whore, or leaving town to visit their "Aunt" for 9 months.
Also, sometimes, it will still happen. A teen girl WILL have sex with a boy. You'd like to hope that it wouldn't mean thereafter that she will stay sexually active weekly forever at that point. You'd like her to be able to see it as a whoopsie, a mistake, and go back to living more chastely for a few years.
What kept them from going all the way in the back seat? Fear of losing their reputations.Reputation, aka what other people think of you, is important.
Fear of being hurt.How exactly does it hurt?