A Theory of Marital Sexual Life

Why does the frequency of marital sex decrease with marital duration? Does the probability of involvement in extramarital sex increase or decrease with marital duration, and why? I develop a theory to answer these questions. 1 apply the law of diminishing marginal utility and human capital theory to explain the basic observed decline in the frequency of marital sex with marital duration. Based on the above explanation, I develop a discussion on the relationship between marital duration and extramarital sex, and I derive two hypotheses, which are supported by statistical analyses of the National Health and Social Life Survey data. Key Words: extramarital sex, gender, marital sex, theory. It is well known that marital duration negatively affects the frequency of marital sex. However, we know little about how martial duration affects extramarital sex. Extramarital sex has enormous disruptive potential for marriages, and it is frequently cited by divorced persons as a prime reason for the dissolution of their marriages (South & Lloyd, 1995). Therefore, a better understanding of the factors influencing the frequency of marital and extramarital sex should be of great theoretical and practical value. However, factors contributing to these two types of sexual behavior are not well understood. This article develops a theory that explains the basic observed patterns of sex between marital partners and makes two predictions concerning extramarital sex. Previous research reports that the frequency of marital sex declines with marital duration (Blumstein & Schwartz, 1983; Call, Sprecher, & Schwartz, 1995; Greenblat, 1983; James, 1981; Jasso, 1985; Kinsey, Pomeroy, & Martin, 1948; Kinsey, Pomeroy, Martin, & Gebhard, 1953; Masters, Johnson, & Kolodny, 1992; Trussell & Westoff, 1980; Udry, Deven, & Coleman, 1982). Although aging is correlated with this decline, Blumstein and Schwartz (1983) find empirical evidence that the impact of age and duration are approximately equal. Moreover, it has been discovered that the declining frequency of marital sex cannot be accounted for by "background" variables such as premarital sex, education, income, and religion (Greenblat, 1983; Masters et al., 1992). Previous studies on marital sex frequency and extramarital sex are strong on empirical analysis but weak on theoretical explanation. Much of the previous research on marital sexual behavior has been in the tradition of "sexual demography", or a mapping of the relationships between sexual behavior and social background variables (Davis, 1974; Edwards & Booth, 1976; Thompson, 1983). For example, in their studies of the frequency of marital sex, most researchers focus mainly on individual or social characteristics and on social control, attributing the declining frequency of marital sex to biological aging, attitudes about sex, the work status of a couple, presence of young children, marital satisfaction, race, gender, and religion (Call et al., 1995; Greenblat, 1983; James, 1981; Olson & DeFrain, 1994; Udry et al., 1982). The most commonly cited explanation of this phenomenon is an intuitive one: The declining frequency of marital sex is due to the loss of novelty, which is often referred to as the "honeymoon effect" or the "Coolidge effect" (Blumstein & Schwartz, 1983; Call et al., 1995; James, 1981; Jasso, 1985). Although these studies have contributed to our knowledge of the patterns of marital sex, they hardly go beyond a description of these patterns to develop a theory of marital sexual behavior. Specifically, in spite of an accumulation of evidence that the frequency of marital sex declines with marital duration, this observed phenomenon remains theoretically unexplained; that is, a causal mechanism is not identified. (A theory is a set of explanations that forms a deductive system; a phenomenon is said to be explained if it can be deduced from some initial conditions and at least one postulate. …