How to make my bf cum

So my boyfriend is bisexual, and he leans mostly towards guys, and he used to have a LOT of sex.. he's not even sure what his body count is. now for some girls, that would be a problem, but I just... really don't care, it's his life. the only problem is, it's almost impossible to make him cum. when I suck his dick it takes 10-20 minutes for him to cum, and when we have sex he never cums, which I feel terrible about because I have at least one orgasm when we have sex, and honestly the only thing I want is for him to cum in me, and whenever I ask him what his kinks are he gets shy. Help!