He wants to be used by you for this. He wants to be in service to you for this. Making you feel good sexually and cum, hard and often, makes him feel good emotionally, make you feel good (especially if it’s his cock or mouth/ tongue) makes him feel good physically and sexually, makes him like a man.
Tongue, hands, cock, toys, combination thereof.
So let him.
I doubt he will refuse.
And, ps, if you tell him up front that it’s all about you and he may or may not cum, I still doubt he will refuse.