He does open his mouth to say something in response, but then she starts undressing, and he just ends up standing there, mouth hanging a little open like an idiot as he watches. For just a few seconds, though, eventually closing it and clearing his throat a little.

"Right."

It still takes him a little while longer to actually come to a decision, for a moment just waffling on what to do, but finally he takes a couple of steps into the bathroom, closing the door behind him before he toes off his shoes.