Molly can feel his whole body suddenly tense and she backs off a bit, remembering that this is his first time really and only the second time he's ever had someone touching his naked body like this. Her hands continue their roaming gently but she sits back and stops using her mouth just for now.

"Breathe, Sherlock," she says, looking at him, trying to get him to relax again. She wants to taste him, but she also wants it to be enjoyable for him, not him worrying about coming too soon the whole time. That just seems stressful.