Harville Hendrix relates a story of when he was just married and, off in the distance, he saw his wife's back and noticed that her shoulders were dropping slightly.
He instantly felt that he had married the wrong person. Later, in therapy, he would recall seeing his mother's back, with her drooping shoulders, and how that symbolized
her emotional unavaliability.
He makes the case that we are attracted to our imago, or the composite of our early caretakers and that we choose them so that we can
heal our early wounds. So, it is no coincidence that couples get into conflict because we actually choose partners who will bump up against our old wounds.
He also theorizes that we find partners who can express our disowned parts. So a reserved, formal person would likely find an irreverant, care free person attractive.
The book is a deep, soul searching guide on how to repair and improve a marriage. The book (especially the exercises at the end) will help you learn more about your partner and give you ways to strengthen your marital bond.