Here is a new book in German about the biology of orgasm:
Orgasmus I - Die Biologie der Trennung
Warum wir uns entlieben und wie man verliebt bleibt
by Carmen Reiss
(Orgasm I - The Biology of Separation. Why we fall out of love and how to stay in love)
When I first connected with the ideas about Karezza and the biology of orgasm on the Reuniting website in 2008 it was a big eye-opener. I understood immediately the impact that this "hidden factor" had had on my love history - and therefore on the course of my life.
I've been doing what I can to spread the message. Unfortunately, people with either a religious or atheist background can be deterred by Cupid's Poisoned Arrow itself, due to the esoteric aspects of the book.