Bad at riding dick.. Any suggestions?

My new boyfriend and I recently started having sex and I’m having the same problem as with my previous partner- whenever I’m on top, I can’t really catch his rhythm or ride properly.. He’s the 2nd person I’ve had sex with, so granted I don’t have much sexual experience

But I just don’t know how to make it enjoyable for the both of us- whenever I’m grinding on top he wants it to be faster, when it’s faster we either lose the rhythm after some time or his penis keeps falling out

It’s making me really self conscious about not being good at sex, so I would appreciate any and all advice❤️