Okay, first off child abuse - I hate it. I hate watching about it, and reading about it. I even walk out of the room when I hear about it on the news.
It is one of those things that does happen in the World. We have to live with it going on around us.
BUT:
As everybody said there is a difference between fiction and reality. I haven't read Lolita as the theme doesn't sit well with me but perhaps I should as a learning experience, I am not really sure. I have written scenes like rape, and murder, and sex, and right now I am contemplating a scene in my original story of a fifteen year old girl with her twenty year old cousin. By rights if there was no difference between fiction and reality I'd probably be put in solitary confinement.
Also, one final thing which no one has mentioned before.
Hundreds of years ago thirty year olds, forty year olds, even men in their fifties and sixties were married off to twelve, thirteen year old girls. Then, when a girl had her first period she was married of as soon as possible. It is only recently that practice is disgusting because of the way society has become.
I like the thought that Mother Nature doesn't know the difference.
Edit: I may ship Hermione/Lucius and Hermione/Severus but I never have had her involved in an underage consensual sex scene. It is sixteen in the UK. Legally, here, Hermione could have had sex practically any time in Order of the Phoenix, as she was nearly twelve in PS/SS.