Saving Your Marriage Before It Starts by Drs. Les & Leslie Parrot is hands down the best book about marriage that I have yet encountered. It goes beyond the oversimplified concept of love and respect, and explores the anatomy of love, importance and differences in communication, as well as the psychology of marriage. The book moves quickly, with many engaging (and relatable) anecdotes and gives practical advice that you can more or less imagine how it would apply in your own life. I've read it multiple times, given it as a gift, and continue to appreciate this book. The writing stye is engaging and the content is intelligent. Even though I have read it before, I still find useful insight/reminders within it. Whether you're in the process of tying the knot, already married for years, or a single trying to prepare yourself - this is a worthy read.
And if you're looking for some interesting research on the topic, check out Gottman. He has done quite extensive research on relationships and his findings are quite fascinating. For example, he has identified several key factors in successful relationships and after observing a couple for 5 minutes can with 95% accuracy predict whether a relationship will last or break. Interesting stuff! I enjoyed learning about him and his work in my Family Communication course. These things never get old.