From the back cover of the book: Harvelle Hendrix, Ph.D., has more than 20 years' experience as an educator and therapist. He specializes in working with couples in private practices, teaching marital therapy to therapists, and conducting couples workshops across the country. Dr. Hendrix is the founder/director of the Institute of Relationship Therapy based in Dallas and New York City.
Its not a text book but was used in a psyche class I took a few years ago on Committed Relationships. An interesting book for anyone who wants to understand their relationships better, and not necessarily just for people who are in a relationship that has hit a rough patch.