Dr. Sue
Johnson, the originator of Emotionally Focused Couple Therapy has written a
great book, which has proven to be an invaluable tool for enhancing and speeding
up the therapy process. The book is called "Hold me
tight" and is available via amazon.de.

Another excellent read on the theory and science of love is a book titled "A General Theory of Love" written by Thomas Lewis, Fari Armini and Richard Lannon. This is also available via amazon.de