Mental block with sexy time

I've been in a relationship with an amazing soul for a little over a year now. Of course we've had our little arguments here and there, but this guy is nothing short of amazing. Open to talking out problems, supportive of my crazy ideas, makes me laugh, the sex is out of this world, and he still even opens doors for me ☺️ I'm the type of person who thinks they can handle all their problems on their own and I've had an issue for the past month that's put a horrible strain on our relationship. Over the past few weeks every time we've started to fool around and get into having some sexy time, I can't get into it. I've tried to explain it to him, but he feels as if it's his fault. Don't get me wrong, my man is crazy attractive and I'm still very into him. But it's almost like this mental block that I just can't shake. Has anyone else had this kind of issue and if so what did you do about it?