"You can talk all you want to about Schnarch's level 6, but I'm not quite sure how sustainable that is when a woman's sexual desire can so easily disappear, dropping you right back to level 0. I mean, you can't stay at level 6 without at least a reasonably strong sex drive on the part of both partners, no?"
It becomes more than an issue of sex drive, ssmguy.
For instance, being an athlete means one thing, and being "in shape" means another thing. Being "in shape" typically means that a person is trying to do some regular exercise because they know it is good for their body, or because they are trying to lose weight. Usually this person will struggle with the regular exercise. It will be a chore and a burden to them, but they may be able to keep it up because they want to be "in shape" badly enough.
But an athlete will exercise because he/she needs and wants to and because their body will automatically want to do it for its own sake. An athlete's body will exercise itself if you don't give it an outlet. I'm an athlete and here's an example: when I haven't given my body proper outlets for exercise in a few days, I find myself automatically doing full squats while I am drying my hair. I don't even notice it at first, it just happens. Its not because I want to be in shape, its because my body has its own agenda.
Something similar happens in level 6 sex, ssmguy. Your body is no longer just focused on getting an orgasm or getting that sexual release or on seeing your partner naked. Instead, your body and your mind begin to engage in a new way of expression together. As a united front, your body and your mind begin to have their own agenda. It is less about sex and more about fulfillment.
Yes, just "sex" will ultimately wear anyone down, even someone with HD. It will ultimately get boring if an HD person has unlimited sex...if it is "just sex".
But there is actually something more than "just sex" available to you. You can find it through a lot of reflection, soul searching, sincere desire to reach the new place with your partner, and with a lot of education.
Right now, it sounds like you believe you have yourself and your body pretty much "figured out". But you would have to toss aside all your assumptions about yourself in order to reach level 6. You would have to have a beginner's mind and allow the world to teach you something new about yourself. You are likely placing a lot of value on trying to achieve a mind blowing orgasm, but this is not the right direction to go if you want to reach level 6.
It also sounds from your post that you are confusing sexual pleasure with sexual fulfillment. They are not the same thing and have little to do with each other. Pleasure is simply a function of the body, that happens when you are touched or are touching in a certain way. In itself it is meaningless and harmless...but also it cannot really give you anything new or teach you anything about yourself. Whereas sexual fulfillment is about your mind and your emotional life...there are places within your mind and emotions which will astound you if you give yourself the chance to reach them.
For now, don't think about another partner as the only way you can fulfill your sexual mind and emotions. Think of your wife. She will most likely totally blow you away with what she is capabale of. I wish you knew Cinco's history better...his wife seemed completely unable to feel sexual and she told him this under no uncertain terms for many years. She convinced him and herself that she just wasn't sexual and that was that. And now...they are breaking through that old assumption and finding it wasn't true, it was only believed. There is a difference between what is true and what we believe in almost every case.
I think your first step should be to just slowly open yourself to the following ideas:
1. YOU and your sex life are far more complicated than simple sexual pleasures...there is so much more to sexual fulfillment. Begin to meditate upon a sexual fulfillment that is like nothing you ever considered before, but leave the partner in your meditations as your wife for now.
2. Your wife can get there from here, just as you can. Its going to require some work but it will be less work than you think. Keep thinking about that: less work than you think, less work than you think.
If you could start here, the rest will have a chance to begin to develop.
Finally, you said: "I have a impression (which is probably a distorted perception) that women's sexual passion, even if strong at a given moment, is in the long run fleeting, fragile, situational, flash-in-the-pan, and can disappear at any moment. Do one thing wrong, or say one thing wrong, and poof it's gone. If a woman is the least bit tired, or if anything went wrong that day, even an HD woman is totally sexless. Probably wrong, but that's my unshakeable impression."
Dear, I opened this entire thread just to challenge your position on this using myself as an example.
I personally know dozens of women who want it ALL THE TIME and don't stop wanting it just because their man did one thing wrong.
Trust me that for now, this is the least of your worries. Women want sex, believe me.
But as I said above, both men and women will tire of "just sex" eventually. It has to be more than "just sex". Hang in here and maybe we can help you figure out how to get to more than "just sex".