“Therefore a man will leave his father and mother and cling to his wife.” That is the seemingly simple prescription for marriage in Genesis. Yet as the Torah proceeds, there is polygamy (Jacob has two wives; David and Solomon, many more), provision for divorce (see Deuteronomy 24), concubinage (Abraham and Hagar; Jacob and Bilhah; and many more), adultery (Hosea and Gomer), and abandonment (David, again). In other words: Things were never that simple.Perhaps all of this will come as a comfort to all of those navigating the increasingly tricky world of 21st-century dating and romance. These days, countless sexual partners are available at the swipe of a finger; women are regularly choosing to be single mothers; marriage has been broadened to include same-sex couples; heterosexual marriage itself is radically transforming. A recent New York Times Magazine cover story profiled several couples in open marriages. And a Philadelphia news station carried a report about “sologamy”—people “marrying” themselves.The first statement the Bible makes about human nature is that “it is not good for a man [person] to be alone.” But loneliness is not, as we know, the same as being alone. When Chekhov wrote, “If you wish to be lonely, marry,” he was giving ironic edge to a keen reality: The ability of another person to fulfill our needs is limited, and the human need for intimacy is limitless.I should know. I myself am a divorced rabbi. And I counsel married, separating, and divorcing couples who struggle to find enduring and satisfying partnerships. Recently I conducted an extended discussion with a number of young singles and married couples, and one clear consensus was: This is not easy.Many of them talked about being plagued by infidelities. Yet sex alone is not a sufficient explanation for the difficulties of monogamy. Clearly, a great deal of infidelity is sexual, but attraction to another person is more than genital. The reality is that no one person is sufficient to fill all the niches in our character. Even the most guarded among us can find herself being drawn to another person who awakens a curiosity or interest that had lain dormant. When people work most of the day, how do you prevent them from being drawn to others who work alongside them, share their interests, and know more about their lives than many a spouse?The traditional rules prohibiting everyday interactions between men and women may be sexist and ultimately lead to various problems of their own, but the rules have a certain iron logic. Even the most casual conversation can lead you to a deeper interest in another person, and where there is attraction on an emotional level, there is often sexual attraction as well.But the vast majority of people I know aren’t going back to the 1950s or following the example of Mike and Karen Pence. In an open society, everyone understands that monogamy is a choice. We live longer and know divorce is always possible. Couples get married now with that “out” hovering. Whether because of a prenup, or premarital counseling, or the experience of friends and family, no one can pretend divorce is never an option.So what wisdom can Judaism offer to these quandaries? What advice should a rabbi offer to young couples just embarking on married life? Here are my suggestions.Find a Loving FriendFor a long time now, marriage has not been the purely social arrangement portended in traditional societies. The ketubah, the Jewish marriage contract, is essentially a document ensuring the economic care of the woman, with none of the flowery romanticism usually found in the (mis)-translation. But in the Jewish wedding ceremony, there is a beautiful phrase sung in the sheva berachot, the “seven blessings”: rayim ahuvim. It means “loving friends.” Passion fades, but friendship, if we are lucky, endures. To have a friend for life, with whom you share the deepest experiences and also the daily difficulties, is perhaps the best arrangement the world affords to restless souls.Be Somebody’s SomethingEven as we crave sexual freedom, the emotional basis of monogamy endures: We want there to be one person whose principal focus in the world is our well-being. We orient ourselves in the world by the magnetic pole of another person. Anna Freud, daughter of Sigmund and herself a renowned analyst, tells of having seen a little girl wandering around London after the bombing killed her family, crying, “I am nobody’s nothing.” To be somebody’s something, securely and invariably, is what marriage promises, and what open marriage, for all its seductions, threatens to destroy.There is a beautiful scene in the Talmud when Rabbi Akiva has been away for years building his reputation and his academy. When he returns home his wife, Rachel, approaches to embrace him. Akiva’s students start to move her aside, and he stops them and says, “All that I am, and all that you are, is hers” (Nedarim 50a). Akiva had many students and disciples, but she was the person with whom he shared an intimacy no one was permitted to breach.Seek Out Meaning, Not HappinessAfter the breakup of his own marriage, the English writer Evelyn Waugh wrote to a friend: “Fortune is the least capricious of deities, and arranges things on the just and rigid system that no one shall be very happy for very long.” Americans have mostly lost the talent for unhappiness. Earlier generations did not expect that life would be as frictionless as we try to make it. They took suffering as the inevitable lot of life; we more often see it as a fundamental injustice to be corrected. This, along with an increased emphasis on individualism, makes us temperamentally less suited for the stresses of life in general, and married life in particular.Many years ago I told a couple at a wedding that they were wise for not seeking someone to make them happy, but rather seeking someone to make them better—for in finding someone to make each better, they will be happy. Growth and challenge are integral to happiness. When the Bible calls a partner an ezer k’negdo, it means literally a helper-opposite. In other words, someone who both encourages and challenges.Be Ready for ChangeWe think of ourselves as steady state, but studies show how much we change over the years, even in matters we thought enduring. Our tastes change—musical, culinary—but also our ideas. Jewish tradition teaches that Solomon wrote the Song of Songs in his youth, Proverbs in middle age, and Ecclesiastes in old age. The first is a passionate love poem, the second balanced proverbs on living, and the third, a weary, wise reflection on all things “under the sun.” So when in Ecclesiastes, the third of the books, it says that you should “enjoy your life with the woman you love all the days of your life,” you know that it is a different sort of love, one tempered by a lifetime, embracing time and change.The same rule that applies to parenting applies to loving: You have to give the other person space to grow. Rabbi Milton Steinberg once described our task in life as “holding with open arms.” We need others to grow not only for their own sake but as our partner grows, they have new things to give.Share ValuesEven granting the changes of life, we must choose people who share our fundamental values. The weight we give to career, family, faith, honesty, and intimacy needs to align with the person we have chosen. Many Jews speak about the concept of bashert, that there is one person for whom we are destined. I believe there is not a single person, but that we can shape our lives with different people, and perhaps even will throughout our lives. But the greatest goal is to find one person with whom you can grow, with whom you can share the moments great and small.When God calls Abraham, he says, “you go”—and the “you” in Hebrew is singular. But Abraham goes together with Sarah because the two of them are one.We all need many other people to support us, to befriend us, to take care of each other’s needs. One person cannot be everything, and friends throughout life are essential. Yet, in the Jewish wedding ceremony, we refer to the Garden of Eden. It is not only a reminder of paradise but of a deeper truth about marriage: Adam and Eve were, for each other, the only ones in the world.Everything has changed since the time of the Bible and the Rabbis—our language and technology and even many social arrangements. What has remained the same is the human heart. And our tradition understood it profoundly and speaks to our hearts today with the same force it did 2,000 years ago.***Like this article? Sign up for our Daily Digest to get Tablet Magazine’s new content in your inbox each morning.