Look at her ride him. I love the apparent disparity in body language here. He is tense, grimacing…struggling to preserve his manly potency.
Conversely, she appears relaxed and in control; amused with his struggling, while coaxing him towards capitulation with the effortless rocking of her hips.
I can just imagine her calm, smirking face looking down at him.. as if to ask ”Having trouble big boy…?”