[We both already knew, and she wonders what it is that he thinks he already knew, what he read in the poems she showed him.

She wants to tell him that he doesn't love her, that he's just infatuated because she's the first person to ever really pay attention to him. That feels too cruel, though, to point it out, too condescending, and she knows it would only make things worse. It'd just be an insult, to try to tell him how he feels.]

You deserve better. [Than her, when she's too twisted up to give him what he wants.

She doesn't give him time to reply before continuing:] We don't have to kiss anymore, if you don't want to, but I've already said that you don't have to stop on my account, and that's still true.

[She's told him that she likes kissing him, that she wants to, but she'll stop if he wants to.]