The Seven Principles for Making Marriage Work: A Practical Guide from the Country's Foremost Relationship Expert by John M. Gottman and Nan Silver. On of my mentors & teachers, John Gottman provides a clear understanding of what makes marriages work based on 25 years of studying couples with long term successful relationships. It's the "bible" for "coupleships."
After the Affair: Healing the Pain and Rebuilding Trust When a Partner Has Been Unfaithful by Janis Abrahms Spring and Michael Spring. Nothing is more devastating the finding out your partner has had an affair. Janis Springs is a Connecticut therapist who deals only with marriages torn apart by infidelity. She offers hope and reassurance that as crazy as you feel--like your whole world is out of control--is perfectly normal. And that if you both want to work at it--you can make the marriage work.
Getting the Love You Want: A Guide for Couples, by Harville Hendrix The founder of the Imago Workshops, Harville presents a clear picture of what happens that we go from romance and not getting enough of each other--to not wanting to have anything to do with each other. In a loving manner he explains how some of this disillusionment is perfectly normal. And how we can use to actually build more closeness and affection in our relationships.
How Can I Get Through to You? Closing the Intimacy Gap Between Men and Women by Terrence Real. This book may not be for everybody. Terry Real calls them as he sees them and he talks about the difference between how men and women are raised in our culture and how those differences play out in the emotional satisfaction we get from marriage. If you like a straight shooter who pulls no punches, this book can be very helpful.
The Five Love Languages: How to Express Heartfelt Commitment to Your Mate by Gary Chapman. In a fun and self-revealing way, Chapman explains how each of us has our own "love language" a way that we feel cared for. For some of us it is words, for some of us it is physical, form some of us it is gifts. He helps couples figure out what their "love language" is and how they can show love to their partner in a way they can understand and appreciate it. I've never recommended this book to a couple that they didn't fully enjoy it.