Sex at Dawn: How We Mate, Why We Stray, and What It Means for Modern Relationships – by Chrisopher Ryan And Cacilda Jetha
Directly challenges ideas prevalent in evolutionary psychology that we are naturally monogamous. Includes a great deal of research and is intelligently written. Will help those seeking some understanding of why they stray or why their mate has strayed.
Mating in Captivity: Unlocking Erotic Intelligence – by Esther Perel
A book that opened my eyes to what I’d seemed to intuitively understand but could not put to words. Space, distance, and unfamiliarity fuel eroticism. Objectifying our partner in a playful way can light or keep the fire lit in our relationships. On the other hand, our drive for security, reluctance to take risks, can smoother the erotic flame.
Masochism 
– by Lyn Gowan
A Jungian perspective on masochism. This book interested me in that it suggests those who don’t recognize, or become conscious of their inner, unconscious archetypes are often doomed to live them out.
The Ethical Slut – by Dossie Easton
A sensitive description about navigating the potential pitfalls and developing the necessary skills to embrace and enjoy the infinite possibilities of open relationships. Covers important topics like jealousy, handling conflicts, and defining boundaries. One of the best books on the subject.
The New Topping Book – by Dossie Easton, Janet W. Hardy
A solid and sensitively written guide on how to top. This is a good book for a novice. Though you’re not going to learn how to tie a knot here, you will learn how to think about and prepare for a scene, get into role, manage the scene, end and engage in aftercare. Touches on the joys and pitfalls of topping.
Sexendipity 