This is an excellent book about understanding how couples' relationships work. You may be put off by all the "four points of balance" and other TM theories - sometimes it sounds like a math book - but don't be. It is long but it's absolutely fascinating. (Thanks also to the other reviewers. A lot of work and thought has gone into some of them).
The message can seem somewhat bleak. You get to fully understand where your partner is coming from by the conflict of "differentiation", because normal communication doesn't work. Then you take it from there and try to act as a team to deal with the problem of sexual mismatches. But understanding can be a great help in and of itself.
The stories in the book are very positive, however, with very good outcomes. This may be surprising given the conflict involved and the amount of theory, but I guess these couples loved each other in the first place, and that is the big plus we all forget about.
Another book which focused on the working of the relationship as the root of the lack-of-desire problem was Rekindle Your Love Life. It basically says that one partner has become stressed and fearful about sex, and it has a more down-to-earth program of changing your own negative behaviors and changing the way she sees you. The man stops the cycle of frustration and rejection, then rebuilds the sexual confidence of the woman, and only then does he start working on rebuilding the sex. It's a very positive ten point action plan, and very easy to follow - and interestingly it concurs with a lot of the theory in I & D - especially the issue of dealing with the constructed image of yourself in your partner's mind. Although I learned a lot from Intimacy and Desire, Rekindle Your Love Life offers a more positive plan to deal with a sex-deprived marriage right NOW. Rekindle your Love Life and Reignite your Relationship: A Practical Plan for People in a Low-Sex/No-Sex Relationship or Marriage
I have a feeling it might be other therapists who get the most out of Dr Schnarch's work.
On the principle that the best way to deal with frustration and anger is to understand a problem, this Intimacy and Desire book will certainly help more than Passionate Marriage, which though good, was a little too theoretical. Especially if you are a contemplative type of person.