There are numerous books, videos, workshops and more that are based on scientific evidence that can strengthen marital relationships.
Hawkins, A. J., & Frakrell, T. A. Should I Keep Trying to Work it Out? A Guidebook for Individuals and Couples at the Crossroads of Divorce.
Useful guide and workbook for couples to use in exploring and strengthening their relationship. Avaliable for free.
Tara Parker-Pope, a writer for the New York Times began writing this book in response to her own divorce, but has put together a very readable summary of the current scientific knowledge about the factors that lead to divorce or, on the other hand, can strengthen marriages. For example, she discusses the what scientists have found about the consequences of fights and the biological benefits of marriage and healthy relationships. She also specifically discusses sex, wealth, and gender in relation to marriage. She cites the work of John Gottman whose “love lab” research have identified the major factors that escalate or resolve couple conflicts. Parker-Pope provides quizzes and tests throughout the book and explains what the results mean and how couples should go about either strengthening these results or fixing them. Overall, this book is great for couples because it takes many scientific studies and are explained in ways that any ordinary couple would be able to understand and use in their own lives. (Summary contributed by Jeremy Kanter.)
Gottman, J. Short video on the best predictor of divorce