I NEED HELP!!

I love my boyfriend so much, I’m certain that’s the man I’m going to marry.

Last night we went out to eat and had some drinks, came home, and had sex. I was looking forward to it all night. He was looking fine af. However, once we started having sex I don’t know what happened but I wasn’t enjoying it at all. I just wanted it to end and was just “there”. (This is really bad)

He noticed, and I was honest and told him idk why but I just wasn’t there. My head wasn’t in it. Obviously he feels like it’s his fault and that there’s something wrong that I’m not attracted to him anymore and I feel bad bc that’s not the case. Now things are all weird between us and I don’t know what to do...I feel like he’s going to break up with me idk what to do 😢😢😢😢