Orgasm

People always say that after an orgasm, your mood is supposed to be lifted and you're supposed to feel happy and stuff. Well after I have an orgasm, I usually feel really sad afterwards and kinda dirty/guilty. People always say stuff to me like "you just have to embrace it and be happy and not feel bad about it!" But it's an involuntary feeling. I'm very comfortable with my sexuality, I love sex, I love my body, I've been a sexual person since I was maybe 9 years old, I have no problem with it. But after I have an orgasm, I just don't feel good and I don't know why. Does anyone know why?