He smiles as he feels her arch her back slightly; it's gratifying to feel her squirm over such a simple touch.

He breaks the kiss for a moment, so he can have a second to breathe; he's not sure whether it's lack of air or the situation that's making him feel slightly light-headed. Once he's taken a breath, though, he takes the opportunity to take another step, trailing light kisses down her jaw to her neck.