IN fairy tales, marriages last happily ever after. Science, however, tells us that wedded bliss has but a limited shelf life.

American and European researchers tracked 1,761 people who got married and stayed married over the course of 15 years. The findings were clear: newlyweds enjoy a big happiness boost that lasts, on average, for just two years. Then the special joy wears off and they are back where they started, at least in terms of happiness. The findings, from a 2003 study, have been confirmed by several recent studies.

The good news for the holiday season when families gather in various configurations is that if couples get past that two-year slump and hang on — for another couple of decades — they may well recover the excitement of the honeymoon period 18 to 20 years later, when children are gone. Then, in the freedom of the so-called empty nest, partners are left to discover one another — and often their early bliss — once again.

Read more at New York Times.