I’m (23F) trying not to be nervous when I’m sexually intimate with my friends with benefits (26M) tonight or ever?

I’ve been sexually intimate with guys before, I just have never gone the whole way. How come? I’m almost embarrassed to say, but I will anyway. The last guy I was with a friends with benefits, we tried to have intercourse. It failed miserably because I ended up becoming too “tight” for him to enter inside me. I bought lube a couple days later but we ended things before we could attempt again. The guy I initiated the FWB said he’s understanding and will take things slow with me in regards to going all the way. I just need to figure out how to not panic in the moment. I really am attracted to this man. He’s coming to my place in about an hour or so.