It took me a few years (from around that age) and some maturing to really appreciate and understand Edgar Allen Poe's (more famous) works, so if that offers a comparison, that may help you, I hope?

I read The Shining at 13, which has content worse than "kissing," and i'm not scarred nor permanently ruined forever. in my opinion, i'm turning out relatively well. Sooo, I don't see how the books would be inappropriate or toxic for your child.