This is National Marriage Week, and it is fitting that the week ends with Valentine’s Day. After all, commitment of marriage vows provides the foundation for the lasting love that is heralded in the holiday greeting cards.

Sadly, throughout the past 50 years, marriage rates have plummeted, while the rates of cohabitation among couples have soared tenfold. And, tragically, many of the couples who began living together were among those who had experienced the pain of parental divorce and hoped that giving their relationship a “test drive” would help ensure its longevity. Yet studies have discovered findings to the contrary: Cohabitation is associated with lower levels of relational quality and a greater likelihood of a relationship’s dissolution.

Sociological research has revealed that, on average, cohabiting couples tend to report lower levels of closeness, love, and satisfaction than married couples. In addition, studies have found that cohabiting couples have substantially lower levels of commitment to their partners than their married counterparts, and the anticipation of the dissolution of the relationship among both cohabiting men and women is twice as high as that of their married counterparts.

Cohabiting couples are more likely to separate, less likely to reconcile after a separation, and more likely to experience infidelity than married couples. In fact, even the subsequent marriages of men and women who previously cohabited are less likely to survive: Compared with married couples who did not cohabit, those who did tend to be less satisfied with their marriages and more likely to divorce. In sum, “sliding” rather than deciding to marry does not bode well for the longevity of a relationship, as inertia might move couples who otherwise would not have married to tie the knot.

The commitment made in marriage is the bedrock of a stable and fulfilling relationship. It provides an environment where love can take root and blossom—even through periods of “rough weather” that may occur along the way. Valentine’s Day reminds us of that deep human desire to build and experience enduring love—and National Marriage Week keeps us focused on the relationship with the best track record of securing it.