It is well known that one of the Ten Commandments is the prohibition of adultery. Extramarital sex has historically been a man’s game, since the male sexual desire is stereotypically assumed to be uncontrollable. A recent survey by the National Opinion Research Center has shown, however, that the number of married American women having adulterous affairs has nearly doubled over the last decade. Today, 21 percent of men admit to having such affairs while 14.7 percent of women now admit to having them.

Sociologists explain that women today are more willing to cheat since they have stronger careers and aren’t as worried about the financial loss they would incur in a divorce. A recent Pew Research Center poll showing that working mothers are now the primary “breadwinners” in 37 percent of American homes (up from 11 percent in 1960) seems to bear this out, as these numbers roughly match the proportion of men and women having affairs. Most of these breadwinning women are single mothers, but 40 percent of them are married and earn more than their husbands. Perhaps it is true that when women began to enter the workforce in greater numbers and rise in the corporate world, they learned from and now emulate corporate male behavior.

In What do Women Want?, Daniel Bergner notes that women may be no different from men in their struggle with monogamy and desires for sexual novelty , although there may be differences depending on the situation. For example, research on rhesus monkeys demonstrated that males initiated sexual relations when the monkeys were kept in smaller cages, but in larger spaces the females initiated sexual relations. Significantly, this and other findings have occurred at the same time that the number of women in scientific research has soared. We hope that science has passed the era when scientists could claim that women suffered from “hysteria” (based on the Greek word for uterus), irrational behavior supposedly caused by disturbances in the uterus.

One might think that monogamy was considered to be against the norms of evolution, since a male biologically wants to have as many offspring as possible. Analysis of various animals living with their brood show that anywhere from 10 percent to 70 percent of their offspring have a father different from the male animal currently staying with the brood. Professor David P. Barash of the University of Washington famously quipped, “Infants have their infancy; adults, adultery.” Even among primates (which include humans), more than 200 species are not monogamous. However, British scientists have found that in the three species of primates in which monogamy evolved, it did so after a period where males had earlier committed infanticide. In reaction, fathers began to remain by their children and mothers to protect them from rival males, thus establishing the monogamous nuclear family. The virtual universality of this system among humans, and its staying power across civilizations, argues for its value.

Even among other species from beetles to baboons, while exogamous sex occurs, one mate will often react with a ferocious jealousy if it observes the other straying. Promiscuity may be necessary among some species for survival, but that does not mean that these creatures like it.

Marriage is one formal marker and arrangement for monogamy. In the Jewish tradition, marriage is a central institution, and Rabbi Joseph B. Soloveitchik wrote about this unique commitment:

On the one hand, the great covenant [of marriage] has been compared by the prophets time and again to the betrothal of Israel to G-d; on the other hand, the ordinary betrothal of woman to man has been raised to the level of covenantal commitment. Marriage as such is called berit, a covenant. Apparently, the Bible thinks that the redeeming power of marriage consists in personalizing the sexual experience, in having two strangers, both endowed with equal dignity and worth, meet. And the objective medium of attaining that meeting is the assumption of covenantal obligations which are based upon the principle of equality. Hence, we have a clue to the understanding of the nature of matrimony. All we have to do is analyze the unique aspects of covenantal commitment and apply them to the matrimonial commitment (Family Redeemed, 41-42).

Knowing how hard it is to find the perfect partner, the Rabbis taught: “It is [as] difficult [for G-d] to match up [a man and a woman for marriage] as it is to split the sea (Sotah 2a).” Elsewhere in the Talmud, the Rabbis debate whether the primary goal of marriage is to produce offspring or about the marriage itself:

Rav Nachman said in the name of Shmuel that even though a man has many children, he may not remain without a wife, as it says: “It is not good that man be alone.” But others say that if he does have children then he may abstain from procreation and he may even abstain from taking a wife altogether (Yevamot 61b).

But even those who subscribe to the latter position, that it is not obligatory to get married, must agree that it’s still desirable and good (i.e., not legally required but clearly very good and important) to marry.

Rav Soloveitchik further explains:

Within the frame of reference of marriage, love becomes not an instinctual reaction of an excited heart to the shocking sudden encounter with beauty, but an intentional experience in reply to a metaphysical ethical summons, a response to the great challenge, replete with ethical motifs. Love, emerging from an existential moral awareness, is sustained not by the flame of passion, but by the strength of a Divine norm whose repetitious fulfillment re-awakens its vigor and force. The marriage partners, by imitating G-d who created a world in order to be concerned with and care for it, extend the frontiers for their communal living to their offspring, and by questing to love someone who is yet unborn, defy the power of erotic change and flux. The ethical yearning to create and share existence with someone as yet unknown redeems hedone by infusing it with axiological normative meaning and thus gives it a new aspect — that of faith. Since our eternal faith in G-d is something which defies rationalization, the mutual temporal faith of man and woman united in matrimony is just as paradoxical. History does not warrant our unswerving religious faith; likewise, utilitarian psychology denies the element of faith in the marriage institution (Family Redeemed, 42).

No one claims that monogamy is easy. We know from psychological studies that young people often have cognitive skills that are still evolving, and it is difficult to tell whether two people can grow compatibly over decades. The choice of a partner is a serious matter. Honest and loving marriage is central to the Jewish faith. We must do all we can to collaboratively preserve the holy covenant that strengthens our families and societies.

We must protect our own marriages and the institution of marriage. Adultery, as one of the many causes of failed marriages, must be rejected through ethical conviction and spiritual commitment. We must all have personal moral accountability, legitimate caring for our spouses and children, and Jewish commitment to the pledge of monogamy and shared covenant of love and devotion.