I think he hates sex with me

Now let me explain. I think he hates it because I can't cum with him, not because I'm bad or anything. Now, cumming is a huge deal for him because other guys have even made me squirt, and I can occasionally get an okay orgasm. It's so bad he's even threatened to leave me because of it, I tell him all the time I don't care, honestly I prefer masturbation over sex pleasure wise, and when I tell him how to change it's "I tried it" or " I do it already" he makes me feel it's my fault while at the same time putting himself down.

I love him, and he's the only man I see myself marrying, but.... he won't change, and when I say "hey babe can we switch it up" he acts like it's the biggest insult. I am serious when I say he has in fact ended things as a result of this, but only when I told him I'll look for other guys, he has a weird kink of me fucking other guys, did he take me back. He's very selfish during sex but denies it. What's worse is he comes over just for sex, only occasionally, and every time we make plans s, last minute he suddenly has plans with his family, which means I can't get mad because it's is family. I know he wants to marry me, as he talks about it all the time, and I want to marry him too but...... I really feel like I can't