That's an interesting application of logical analysis to the problem, but a dialectic approach might be more useful. Actually, Schnarch uses dialectic synthesis to describe the process of differentiation. There is a diagram in PM that looks like a triangle with one apex at the top and two apexes at the bottom. The bottom two apexes have Dependence on one side and Separation at the other side. When you can assimilate the healthy aspects of these seeming contradictions and transcend them, you achieve Differentiation, which is at the top apex. In another post about phone sex with your husband, you described your opposite reactions to being rejected: how you used to get hurt feelings (internalizing), but now get steamed at your husband (externalizing). These are the two bottom corners of the triangle. When you can synthesize these two fused reactions, you will be able to transcend these feelings and differentiate. My guess is that when that happens, you will be able to cut both you and your husband a break.
Bringing the dialectic synthesis to WB's dilema, his marriage has high desire on one side and low desire on the other side. He and his wife have been able to transcend these opposites by finding a moderate sexual relationship that represents healthy mutuality. But WB sees a dark cloud: he knows his days of conflict aren't over. Instead of standing at the top of his triangle, looking down and enjoying the view, he realizes that he is at the base of a whole new triangle. He knows that there is more conflict ahead and that he doesn't know how or whether he and his wife will be able to transcend it.
This is one of the important aspects of dialectic synthesis. There is almost always another triangle. And when you have reached the top of the last triangle, you have reached the end of history.
"If we will be quiet and ready enough, we shall find compensation in every disappointment." Henry David Thoreau
