funny that you bring this up because my sex drive is clearly in the shitter...
Greg gets wood whenever he rubs my back or whatever too and I get out and out pissed because he goes for gettin laid when all I want is my poor sore back rubbed
So he rubs your back for 30-45 minutes, then he gets laid. Sounds like a good deal for both of you.
Then again skipping the backrub and getting laid still sounds like a good deal for both of you.