Why am I afraid of sex?

I (20M) recently discovered that I have this fear or anxiety about sex that seemingly came out of nowhere.

I have no clue what triggered it, but for awhile, whenever I feel like a situation could lead to sex, it triggered some anxiety or fear in me, and this is regardless of if it involves a male or a female.

The thing that makes it more strange is, I had a few sexual encounters before with my ex when I was 16 and 17, and I don’t recall any fear, nor do i recall her being abusive or anything.

I will also mention, the sexual pleasure leading up to orgasm, or oddly enough, anything involving my nipples starts making me feel very vulnerable and unsafe. This level of uncomfortableness is by no means anything new btw, even before I knew what sex was, I ended up discovering the nipples thing by accident.

As far as my history goes, there isn’t much that I’d think would cause this specific thing, exploring myself a lot earlier than I should have, discovering porn at a relatively early age (around 8). The one thing I’d imagine would cause any issues was a bit of sexual harrassment that happened when I was like 14, but I’d imagine those issues wouldn’t randomly pop up at age 20.

For a bit, I thought it was maybe out of a fear of accidentally getting someone pregnant (fatherhood is terrifying to me), until I realized it wasn’t just afear of having sex with women, but men also.