On a related note, the book 'The Surprising Secrets of Highly Happy Marriages' (author Shanti Feldhahn) independently found many of the same things mentioned in the feature article.

Feldhahn takes a social statistics approach in developing her books. If I recall correctly her work on this book is derivative of interviews and surveys of ~1000 couples and dug deeper into the ones that both spouses rated their marital happiness at the top of the scale.