Sex sex and more sex... help

Hi ladies. I need some advice or just some words to help me figure this out. Okay so, at the beginning of my relationship with my boyfriend, I was recently getting over an ex. Meaning that every time I had sex with my new boyfriend I felt gross at myself and uncomfortable and just felt bad. After passing through that phase or what not we had great sex and i didn’t feel guilty and i enjoyed cuddling afterwards. But now, we’ve been together for almost a year, and it’s acting up again. I will initiate sex and want it until maybe bout halfway through I feel gross or after I cum i feel disgusted with myself and I don’t even wanna be touched or cuddled or anything. I just.. i don’t know why I’m like this..