An affair: it can rob a couple of their relationship, their happiness, their very identity. And yet, this extremely common human experience is so poorly understood. Affairs, she argues, have a lot to teach us about modern relationships—what we expect, what we think we want, and what we feel entitled to. They offer a unique window into our personal and cultural attitudes about love, lust, and commitment

While having read this book will not ease the pain of learning that one's partner has been having an affair and lying and sneaking around, it may help people to communicate and to allow compassion for each other, and to avoid immediately deciding to end a long-term marriage that may be worth salvaging.

What are we to make of this time-honored taboo—universally forbidden yet universally practiced? Why do people cheat—even those in happy marriages? Why does an affair hurt so much? When we say infidelity, what exactly do we mean? Do romantic expectations of marriage set us up for betrayal? Is there such a thing as an affair-proof marriage? Is it possible to love more than one person at once? Can an affair ever help a marriage?

Perel weaves real-life case stories with incisive psychological and cultural analysis in this fast-paced and compelling book.  She asserts that marriage and relationships can make it through cheating & come out happier on the other side. Betrayal hurts, she writes, but it can be healed. An affair can even be the doorway to a new marriage—with the same person. With the right approach, couples can grow and learn from these tumultuous experiences, together or apart.

This book is moderately inclusive. While much of the case studies are about relationships that are straight or heterosexual, she does mention queer and lesbian experiences. She discusses couples of varying dynamics; dating six months, married 30 years, open relationships, etc and is inclusive of the various relationship models out there today.