Not only can he feel her heartbeat with his hands, but he can also hear it easily (his ears are 'tuned' to only this room and their bodies, blocking out the rest of the building) without taking any extra effort to listen. And the way it speeds up when he touches and kisses her makes him grin, knowing that it is him that is making her feel this way.

(And she is right, in that he would most definitely NEVER hurt her.)

With his mouth on her skin, he kisses over the swell of her breasts - paying equal time and attention to both - before he settles his lips and tongue on one of her nipples, teasing gently in the way he has learned she enjoys most.