Don't want to have sex with bf

Hey guys, I have a problem that's been constantly on my mind for a couple of months now.

I've been with my partner for more than 2 years now. I'm 19 and he's 20. We always had sex and I was always horny until 3-4 months ago. Now, I just can't stand the idea of being physical with him. Whenever he touches me, I feel uncomfortable and I always find an excuse not to have sex with him. We had sex maybe 4 times in the past 4 months. I feel awful about this. I'm constantly wondering if I still love him, if it's normal for me to feel this way..

He is an amazing person, we never fight and he loves me very much. I don't have any reason to be mad at him, so I don't know why the idea of him touching me disgusts me so much. Even kissing him makes me cringe sometimes.

Did it ever happen to you guys? I feel really guilty about this and I don't know what to do, I have no one to talk too.