The Science behind Maintaining a Happy Long-Term Relationship

Plenty of people are pessimistic about the state of relationships in society. Dr. Helen Fisher, author of Why him? Why her? How to find and keep lasting love, senior research fellow at the Kinsey Institute, isn’t one of them. She sees trends like extended periods of cohabitation before marriage and a persistent fear of divorce not only as interrelated, but also signs of a healthy change in attitude toward love.

While marriage was once the start of a long-term relationship, she says, today is...