In America, most marriages fail, either ending in divorce/separation or degenerating into turmoil and resentment. However, three out of 10 people who are married remain happily married for the rest of their lives. A natural question arises here: Is there something that is missing from failed marriages that is common to successful ones?  

In 1986, psychologist John Gottman began an illuminating study of married couples, which was summed up by Emily Esfahani Smith in an excellent Atlantic article a few years ago. In the study, Gottman observed how newlywed couples interacted with each other while asking them questions about their relationship, like how they met, good memories, and how they handle conflict. While asking these questions, he measured their vital signs in order to gauge their physiological reactions as they talked about their relationships. After gathering this data, Gottman sent the couples home and followed up with them six years later to see if they were still married.

The data revealed that there were two distinct types of couples. One group, nicknamed the “masters,” were the couples that were happily married six years later. They felt calm in each other’s presence and were almost always warm and affectionate in their interactions. These couples made it a habit of finding positive ways to compliment their spouse in their day to day lives, even down to seemingly “mundane” things like acknowledging and responding positively when their spouse tries to connect in a small way (e.g., “Honey, aren’t the stars especially clear tonight?”).

In contrast, the other group, nicknamed the “disasters,” often found ways to nitpick each other with criticisms. During Gottman’s study phase, their physiologies showed signs of being in “fight-or-flight mode,” as if they were always prepared to verbally attack or be verbally attacked by their spouse. Not surprisingly, these couples had either divorced or had highly dysfunctional marriages when Gottman followed up with them six years later.

The main takeaway from Gottman’s studies and other research on married couples is clear—it all boils down to kindness:

Much of it comes down to the spirit couples bring to the relationship. Do they bring kindness and generosity; or contempt, criticism, and hostility?

Kindness … glues couples together. Research independent from theirs has shown that kindness (along with emotional stability) is the most important predictor of satisfaction and stability in a marriage. Kindness makes each partner feel cared for, understood, and validated—feel loved.

For believers especially, the results of these kinds of studies about marriage should come as no surprise, but they do validate what we Christians know from the truths of Scripture. In Ephesians 5:28-30, Paul wrote:

Even so husbands should love their wives as their own bodies. He who loves his wife loves himself. For no man ever hates his own flesh, but nourishes and cherishes it, as Christ does the church, because we are members of his body.

Paul gives an intimate and evocative description of the type of love that should be shared between spouses—to “nourish” and “cherish” one another as one would their own body. Interestingly, this image of nurturing love as one would nourish their own body matches up well with how Emily Esfahani Smith sees the nature of kindness—as a muscle that needs to be exercised:

There are two ways to think about kindness. You can think about it as a fixed trait: Either you have it or you don’t. Or you could think of kindness as a muscle. In some people, that muscle is naturally stronger than in others, but it can grow stronger in everyone with exercise. Masters [those in healthy marriages] tend to think about kindness as a muscle. They know that they have to exercise it to keep it in shape. They know, in other words, that a good relationship requires sustained hard work.

During this National Marriage Week, the theme of kindness is an especially fitting one to ponder for all those who are discerning marriage and who are married, particularly those who may find themselves stuck in a rut of marital dysfunction. As Emily Smith has observed:

There are many reasons why relationships fail, but if you look at what drives the deterioration of many relationships, it’s often a breakdown of kindness. As the normal stresses of a life together pile up—with children, careers, friends, in-laws, and other distractions crowding out the time for romance and intimacy—couples may put less effort into their relationship and let the petty grievances they hold against each other tear them apart.

However, there is always hope, and a chance to begin again. For believers, the centrality of kindness in the Christian life is encapsulated in the Golden Rule (Matthew 7:12 and Luke 6:31). It’s a tall order, and we often fail at it. But if spouses keep working toward incorporating kindness into their daily lives together, they will keep the “muscle in shape” and make it the animating quality in a harmonious marriage, year after year.