Why is sex not enjoyable for me

For women a big part of sex is also mental. If you are not into it mentally you won't have a good time. Women are also more likely to have an orgasm through clitoral stimulus and not just penetration.

Because women’s pleasure comes from the clit. And if you’re not aroused, lubricated, into it mentally, prepared for sex (with foreplay) and getting stimulation- it isn’t going to feel good.