"Apologize: If you regularly rejected his sexual advances in the past, this may be a major factor in his lack of interest now. Maybe it's retaliation, but it's more likely he's put his sexual energies into something else (work or hobby) and is not interested in changing. He may be afraid you will lose interest again, and then he would get hurt all over. Or maybe he just got so burned out by sexual rejection that his sex drive just died.
If there is a significant ongoing disagreement between the two of you this can also harm his desire/ability to be sexual with you. Hurt feelings may continue even after something is resolved or buried, so past problems could be an issue too. If he feels you take him for grated, don't respect him, or expect unreasonable things from him, these can all hurt his sex life with you."
