Having an orgasm for me, during sex, is a function of tuning into my partner's directions and hints and basking in the experience of feeling every inch of their body.
This might have spelled the end more clearly than I understood. She didn't want sex. She fought about sex. She complained about how I asked for sex. She always got off when we had sex, but she had started not-caring about the LOVE in the experience. And that was a deal killer, both in the moment and in our marriage.