Why do I feel sad after sex?

I feel sad and distant after sex or foreplay. Even if I like the person a lot.

I’m female, 22, never been in relationship before but I’ve had around 15 sexual partners since I was 18.

My only possible explanation for this is maybe because the majority of my earlier sexual partners were mostly casual hookups? And I always longed for more? Don’t know honestly.

I avoid casual hookups now and I haven’t had one in maybe two years, but this weekend I went on a date with a guy I am seriously interested in. I had no intention to have sex with him (as it was our first date) but we made out, one thing led to another, and we ended up doing oral sex. After that I felt kinda distant, despite having such great chemistry with him. He kinda noticed it too.

Anyways I just wanna know if anyone knows what’s up, if this is happening to you as well and what the reason behind it is. Thanks!