For me, it is a combination. One part is the fear that I cannot succeed. Not with my wife. Not with any woman. To the extent I fear I cannot succeed, I am looking for an excuse not to even try. My wife's misbehavior justifies my not even trying. Helps me be more comfortable with my (foolish, unhealthy, shortsighted) choice.

Second, the conflict shows that she is unhappy. If I am going to be unhappy (and I am), at least this way she is unhappy too. I know, not the most loving attitude. But at this point, after trying and failing for 8 years, it hurts less to fight than to cater to her needs with no reciprocation. When I do that, I feel like a wimpy doormat. When I refuse to do what she wants, I feel more powerful.

Dr. Harley would say "don't fight, negotiate to get your own needs met". BTDT. I have given up hope of getting my needs met.