Libido Difference

So lately my libido has been on high compared to my boyfriend's. At the start of our relationship he was the one with the strongest sex drive and I never said no to making love with him even though my libido wasn't up for it (He always managd to turn me on and I'd be in the mood for it) But now that mine is high, his is at its lowest. And even knowing my drive has been crazy lately he...holds back on sex (?) As in, we start kissing and grinding, and I can clearly tell he's hard and ready for it, but he just stops and doesn't want to continue (?) Other times he tells me he doesn't want grinding (while we're getting steamy doing it) to turn into sex.