Why is it so hard to sexually please my boyfreind?

when ever i give my boyfreind a handjob, he insists that i do it really fast with a really tight grip, and he says if i dont do it like that then he barely feels pleasure. i don't think all guys need it to be so hard, and i get really tired doing it....i feel like i"ll never be able to pleasure him enough. what do i do? and why does he feel that way?