Seeing a nude pic of her would help. lol.
She can always knock on his door in a bikini with you watching. Ask him if he likes it or if it would be better without the top?
If he says without the top then show him. Make sure he knows both of you are there.
The husband CAN be a distraction. So initially I prefer just her and I with husband nearby.
But at the earliest possible moment I want her telling him that she is cum filled