Like many of your followers, Carl's letter caught my attention also. Having read "lots" of literature over the past 6 years through my marital struggles, I have yet to read how sex - all parts of it, or lack of it - affects a man emotionally. In contrast, there are a plethora of instructions for men and the emotional preparation of their woman in order to have her be "willing" to have sex with him.
Maybe I am more emotional than most men out there, but I see very little written for women to help them understand that the sexual act and all aspects of it have a tremendous emotional impact on men.
As you pointed out in your blog which Carl quotes, it centers around total acceptance. What could be more emotionally devastating than to be rejected by your spouse? How about the "OK, you can have it as I lay here" attitude? Or the impact of being tolerated vs. loved; or the concept that I must be a horrible lover tonight; or not being willing to discuss or experiment with our sex life in order to keep this relationship with the same spark as it started. All this also snuffs out the bond that sex builds and maintains...
None of these make a man feel good inside. So when we feel rejected, inadequate, unloved... is it any wonder we are unhappy, depressed, filled with despair, while living with our clueless mates? (My wife continues to refuse to read your book(s) unfortunately)
Sex in and of itself isn't everything, but the emotions it generates in a man can make or break the relationship!