our different sex drives makes me uncomfortable

I’m someone who’s never been comfortable with sex and sexuality. I’ve never really been into masterbating, and when I’m single don’t ever have urges to have sex or do anything sexual. I recently began dating a guy who has a high sex drive. I lost my virginity to him and I’m his fourth partner. He was comfortable with random hook ups, and is into and comfortable with getting himself off and I’m just different. When we have sex he wants different positions and things to be freaky but I’m just not like that. Our different sex drives make me uncomfortable and when I mention it he always tries to reassure me that he doesn’t expect anything from me but I dont know. I just feel uncomfortable. I’m not experienced and never really cared to be, I’m not sexual or anything and he’s the opposite. How do I deal with it? How do I become comfortable with his masterbating, sexual experience etc. When I’m not like that? I don’t know, it starts to feel like somethings wrong with me