[He can't help it -- he chuckles a little, pressing his face against her chest to try to muffle the quiet sound. He doesn't mean to laugh at her, really-! It's just funny to him, that he can be so inexperienced, and yet...]

I don't think being a pervert has anything to do with it, Rei... I don't think you're supposed to be able to help it. If I'm doing anything right, that is.

[Really, he'd be concerned if after all this, she wasn't excited at all.]