Is it normal that i want his sex all the time?

My boyfriend is the most attractive person I have ever dated before. I am so attracted to everything he does and if I am in the same room as him, I am already wet. He doesn't even realize it because he's never really had a girlfriend before. I'm his first for everything except kissing. He understands my sexual fantasies as being a submissive play toy and he is one of the only people that I can even talk to about it. I call him master during sex and he calls me a bad girl.

Why don't I ever just want to talk about cats or something? The minute I talk/see him I want every part of him. He's kind of a nerd but he's so sweet and I don't understand why I can't control myself. I feel like such a nympho because he is always the one telling me no.