It is all about self-reflection. As the author has spent a long time in an ashram, it has trained him very much in this discipline, which he passes on in this book in every chapter. But it is also about setting boundaries, letting go, clearly knowing your limits.
About part 2 in particular:
I liked rule #4 about your partner being your guru. It depends on how you interpret the definition of a guru, of course, but if we assume that he is our teacher, or as Robert Betz’s German expression sums it up (namely our Arschengel🙂 - sorry, my language - than yes, I would agree with it 100%. People closest to us and to whom we are transparent push all our buttons in a certain way and are the ones who teach us the most. Literally our gurus - like a mirror held up to you in all its glory.
What I also enjoy are the letters at the end of each part. The first one was the love letter to myself (as I should be the number one in my life) and now at the end of this second reading part is the love letter to the partner. Just this whole symbolism to celebrate our love, to make oursself aware of the whole value that a love relationship has. Never to take anything for granted, to appreciate the good and the bad and to learn out of it.