It's not unreasonable to be concerned. The thing is, it's difficult to detangle. He's much more apt to have an interest if she's the one starting it; so his response being sudden wouldn't necessarily make it any less genuine. Still, he's so concerned with treating her well that he doesn't think much at all about what he wants.

Right now, it's an academic question, because his interest is very genuine. Maybe it should be more of a concern that they haven't got walls, much less a door, but it's quiet enough to feel more private than their house full of roommates, nearly. He shifts his weight, sidling a little closer with a wriggle of his hips. Yes, that's okay by him.

He lets his hand drop again to rest low on her back and kisses her a little more playfully. This is probably a better way to waste energy than to get it, but she can make her bed and lie in it if she so chooses.