What is up with the pain while having sex?

I’m 41f and I had sex last week after almost 15 years of celibacy. The guy was gentle, we used lube. So dryness can’t be the issue right? But still it was very painful, we had two sessions in 1 hour duration, but the pain was constant.

My periods are absolutely normal and on time. I’m not perimenopausal, and I am not on birth control meds.

Any advice why it’s happening!?