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.
If you understand your desire and what you want (both in a partner, in a sexual experience, and in life) you can take clear and intentional actions toward that goal. Your desire is your guide and your fuel. Your path is always towards what you want. Tuning into your desire is step one.
Our children have probably learned more about relationships (good and bad) from television and porn. It's part of why all of us are so confused about what makes for a healthy relationship.