It's absolutely possible to be experiencing pelvic pain due to orgasm. Firstly, you live in your body full time, and you're present for every orgasm you have, so I'm inclined to trust the pattern you're seeing. Secondly, I've known more than one person who enjoys sex but actively avoids orgasms for the exact same reason as you.
For decades, a woman named Mary suffered from consuming delusions. Long-lost professional colleagues were meddling with her life; someone was spying on her through a camera in the showerhead; her eldest daughter was conspiring against her and putting poison on her pizza.