He is a sex therapist and works with couples in psychotherapy. While I do not agree with all his concepts, there are quite a few that really help bridge the gap with couples. You get to decide which ideas you will try and which you will not.
Here is a quick summary of a few of his chapters. I encourage you to read the book for significantly more in-depth about differentiation and how it helps.
Confront yourself, your limitations, those things you avoid. Try healthy experiments - new ways of doing things. This will help you tremendously.
Grow in your ability to handle intimacy and tolerate passion. Yes, those are both really hard to do.
If I allow myself to be passionate, to feel my desires, to be enthusiastic, to want and to express preferences, I could be disappointed. If I "show up" in the moment, engage and am true to myself, stating my preferences- then I have integrity, even if I end up not getting the preference. Sure beats not asking, not being genuine or authentic. With a little practice, most people can handle disappointment. If you can handle not always getting what you want, but still asking, you are less likely to sell yourself out. Think of how you grow or kill passion in your own life. Do you still go for the gusto or is that for other people? When you are able to tolerate passion yourself, grow it yourself, watch it impact your relationship.
Allow yourself to be known- put yourself out there- that is how you develop intimacy. Spend quality time with the person you want to get to know. Get information about them and get to know them personally, how they are in different situations. If you know yourself and you know your partner, you have great capacity for being emotionally intimate. Now, you have to make the choice to connect and follow the connection with behaviors. Not all behaviors that are intimate are sexual.
As a sex therapist, he notes following the connection is better than any "technique."