Many Jews and Christians still view marriage as a matter of sex, as opposed to friendship or sharing material goods or inheritance. Prince William will marry a woman in a Christian ceremony later this week: He had better be prepared to give her regular sexual satisfaction. We know that Prince William's parents stopped satisfying each other sexually, turning to others for pleasure in bed. Before they committed adultery, it is likely that Charles and Diana fell short of the sexual expectations of a Christian wedding contract.
Following St. Paul, Christians might argue that marriage is for sex (and that sex is for marriage). St. Paul, like Augustine after him, took lust as a simple fact of life, a sinful effect of the Fall of Adam and Eve. Since lust was natural, it was for Paul naturally a part of marriage. Indeed, lust was the reason why men and women marry. Once a man and wife start having sex, they shouldn't stop. Over the centuries, Christian theologians would pivot onto this rudimentary idea exceptions such as impotence, leprosy, and captivity, even as various theologians questioned the authority of the pope to dissolve marriages which seemed problematic. Should Prince William's bride one day come to suffer from, say, Alzheimer's, he will have to decide what to do with his sexual needs, which are guaranteed satisfaction from his wedding day forward.
St. Paul's influential reference to conjugal rights in 1 Corinthians 7 does not come from out of the blue; the idea that a husband and wife owed sexual intercourse to one another ("conjugal debt") comes from Judaism, with some modifications. Paul declares:
The husband should fulfill his marital duty to his wife, and likewise the wife to her husband. The wife's body does not belong to her alone but also to her husband. In the same way, the husband's body does not belong to him alone but also to his wife. Do not deprive each other except by mutual consent and for a time, so that you may devote yourselves to prayer. Then come together again so that Satan will not tempt you because of your lack of self-control. I say this as a concession, not as a command.
St. Paul does not mention physical infirmity here, but generations of subsequent Christian theologians would take up the matter. Alzheimer's, for example, is a relatively recent phenomenon (it was only "discovered" or named in 1906), and so it is hardly surprising that theologians have not addressed it specifically. Anyone who sees the statistics may understandably worry about coming down with Alzheimer's. Granted, our spouse's sexual happiness may not top our list of concerns, but anxiety about such happiness may nag at us. And Christianity is part of the reason why.
Of course, Christianity sprang from Judaism and maintained much of the spirit of Jewish theology. Christian theology also absorbed some of the sexual asceticism of ancient Greece. Although plural marriage was never allowed in Christianity, it was in Judaism. Jewish law specified that a second wife must be treated as well as a first wife. Exodus 21:10-11 states that a second wife is not to be preferred over a first wife, not even if the first wife happened to be a slave:
If he marries another woman, he must not deprive the first one of her food, clothing and marital rights. If he does not provide her with these three things, she is to go free, without any payment of money.
A free person could be expected to enjoy any right enjoyed by a slave; Exodus 21:10-11 instructs that these rights are to food, clothing, and conjugal relations (oddly enough, shelter is not mentioned).
Judaism took the idea of sexual obligation so seriously as to protect a woman's sexual pleasure, as opposed to simply her right to take part regularly in the sexual act itself. The sexual act failed to fulfill a man's duty if the woman did not feel pleasure, that is, achieve an orgasm. Satisfaction of the wife is commanded; the law is called onah. For centuries, Jewish law permitted a woman to demand a divorce from her husband if he failed to fulfill his conjugal debt.
Rabbinic Judaism coalesced and became the dominant form of Judaism in the sixth century CE, after the codification of the Talmud, or oral law. What principally distinguished rabbinic Judaism was its emphasis on the oral law or oral Torah. The Talmud became as authoritative as the Torah itself. Rabbinic Jewish law separated what Catholic theology would insist on combining: erotic pleasure and procreation. Onah remained a commandment separate from the commandment to procreate. Thus, sexual relations are required even with a woman incapable of conceiving, whether pregnant, nursing, or postmenopausal, no less than they are with one fully fertile, as long as it is done in the same manner as procreative sex. Some authorities even understood the Talmudic permission to engage in "unnatural intercourse" as permitting occasional acts of anal or oral intercourse, even though these were clearly not procreative.
Onah privileged women. The thinking was that men were bold enough to ask for sexual fulfillment; women were not. Furthermore, when a man experienced sexual arousal, his erection made that plain. An aroused woman, on the other hand, was considerably more difficult to detect, anatomically speaking. It was a man's duty to "visit" his wife before making a long journey, on the thinking that she would need to "save up for a rainy day," with regard to sexual needs. Some ancient Jewish thinking seemed predicated on the expectation that a woman yearning for sexual release would stray if her husband were not at her side and capable of satisfying her needs.
In the infamous spot in which St. Paul would later say that it is better to marry than to burn (1 Cor 7), he made the idea of sexual entitlement a reciprocal right. No less than the Jewish rabbis who developed the idea of onah, St. Paul understood the obstacle lust posed to maintaining a happy marriage and preventing urges to take consolation in the arms of a prostitute. Hebrew Scriptures take a matter-of-fact view of prostitutes, arguably more so than do many twenty-first century Americans. The story of Tamar and Judah revolves around prostitution, and Hebrew scriptures address the social freedom of prostitutes: The earnings of a prostitute were not acceptable as a temple offering (this is what charitable organizations today refer to as "dirty money") and priests were not allowed to marry a prostitute or a divorced woman (Leviticus 21:7).
The shadow of the conjugal debt fell over questions of fornication and poor health. The thirteenth-century theologian Aquinas, for example, held that a girl who was engaged to be married already belonged to her husband-to-be. Even if she were forcibly, violently abducted and robbed of her virginity by her intended, it could not be said that she had been raped. Pressing on the notion of debt, many theologians believed that a woman was obliged to have sex with her husband even if it endangered her health. Such a theological belief might become a suspicious excuse today, in the event that a healthy person forced a spouse with Alzheimer's into sexual intercourse. Given how many Westerners object to the idea that a pregnant woman should deliver her baby even if doing so were to pose significant health risks, it seems reasonable to expect significant social opposition today to the idea that a woman should put her husband's carnal needs before her own health.
In the event that William or Kate should become physically or mentally disabled (and therefore incapable of having sex), selfless sacrifice of sexual expectations is the ideal they seem to inherit. In our hyper-sexualized West, forgetting about sex would be asking a lot. Viagra can keep men bucking into their eighties, if not longer. What a lot of loneliness newlyweds have to be prepared to negotiate! And then there is boredom: think of all those marriages in which sex ends, gradually or suddenly. We might argue that the marriage endures after the sex ends, but for many Jews and Christians, sex reasserts itself doggedly. By signing up for a Christian marriage, young spouses seem to be committing to a lot of sex - even after one of them may have stopped wanting it.