It's called XVI by Julia Karr. I'm not far enough in to know if I like it or not, though.
It's about a society in which every girl, at the age of sixteen, gets XVI tattooed on her wrist. It's a sign of reaching the age of consent. Supposedly, some big event changes everything, just as a new boy joins her life.
I should finish it sometime soon. I love recommendations, so if you think of anything, definitely tell me!