ARE marriages today better or worse than they used to be?

This vexing question is usually answered in one of two ways. According to the marital decline camp, marriage has weakened: Higher divorce rates reflect a lack of commitment and a decline of moral character that have harmed adults, children and society in general. But according to the marital resilience camp, though marriage has experienced disruptive changes like higher divorce rates, such developments are a sign that the institution has evolved to better respect individual autonomy, particularly for women. The true harm, by these lights, would have been for marriage to remain as confining as it was half a century ago.

As a psychological researcher who studies human relationships, I would like to offer a third view. Over the past year I immersed myself in the scholarly literature on marriage: not just the psychological studies but also work from sociologists, economists and historians. Perhaps the most striking thing I learned is that the answer to whether today’s marriages are better or worse is “both”: The average marriage today is weaker than the average marriage of yore, in terms of both satisfaction and divorce rate, but the best marriages today are much stronger, in terms of both satisfaction and personal well-being, than the best marriages of yore.

Consider, for example, that while the divorce rate has settled since the early 1980s at around 45 percent, even those marriages that have remained intact have generally become less satisfying. At the same time, consider the findings of a recent analysis, led by the University of Missouri researcher Christine M. Proulx, of 14 longitudinal studies between 1979 and 2002 that concerned marital quality and personal well-being. In addition to showing that marital quality uniformly predicts better personal well-being (unsurprisingly, happier marriages make happier people), the analysis revealed that this effect has become much stronger over time. The gap between the benefits of good and mediocre marriages has increased.

How and why did this divergence occur? In answering this question, I worked with the psychologists Chin Ming Hui, Kathleen L. Carswell and Grace M. Larson to develop a new theory of marriage, which we will publish later this year in a pair of articles in the journal Psychological Inquiry. Our central claim is that Americans today have elevated their expectations of marriage and can in fact achieve an unprecedentedly high level of marital quality — but only if they are able to invest a great deal of time and energy in their partnership. If they are not able to do so, their marriage will likely fall short of these new expectations. Indeed, it will fall further short of people’s expectations than at any time in the past.