The Seven Principles for Making Marriage Work by John Gottman
Without much debate, John Gottman is one of the leading researchers in the field of relationships. Gottman is a clinical psychologist who has been studying relationships for more than five decades. He knows some things about relationships. In this book, he shares seven of the things he knows for sure. The book is insightful and helpful.

Love and Respect by Emerson Eggerichs
We came across this book only recently as we were researching cover designs for our second relationship book Heart Versus Head. It's a deeply Christian read, so if you're not looking for that, steer clear but if you're looking for a book that shows how love and respect are core to what God wants for marriage, this is a good book to start with.

Men Are From Mars, Women Are From Venus by John Gray
People are sometimes surprised to see this book here. After all, we give John Gray some grief for "getting it wrong" on gender. While we still think he did get it wrong on men and women, this is an otherwise thoughtful book. Gray got a lot of important stuff right. He can be forgiven for locking relationship advice into the male-female argument for a couple of decades because he was mostly correct in the late 80s - most Heads were men and most Hearts were women. It's different now but the rest of the book stands the test of time.

Attached by Amir Levine and Rachel Heller
This is the book that started the conversation about attachment styles. It has its fair share of critics but it does a good job of explaining how humans pair up. While the labels can feel a bit judgmental at times, it will provoke some solid self-assessment for both partners.

Fight Right by Julie and John Gottman
Julie Gottman takes lead writing credit on this book from the Gottman's. The book gives some ways that couples can navigate the landmines of conflict. It's a good addition and deep dive into what we talk about in The Couples Rulebook, Rule 13 - Fight by the Rules.