The Seven Principles for Making Marriage Work, A Practical Guide from the Country's Foremost Relationship Expertby John M. Gottmann, 1999.
In his “Love Lab,” Gottmann studied couples and learned how to predict divorce.
His research brought a wealth of information to the field, including the “Four Horsemen”: Criticism, Contempt, Defensiveness, and Stonewalling.
It is a great read that includes a lot of fun quizzes and exercises that you can try with your honey.