Husbands have doubled the time they spend doing housework. One frequently cited study suggested that couples who shared housework equally had sex less frequently than couples who followed a more conventional division of labor. But a forthcoming study of more recent marriages finds that egalitarian couples report no difference in sexual frequency or satisfaction compared to couples who cling to traditional roles — the exception being the about 5 percent of marriages in which the husband performs most of the housework.

The researchers Christine R. Schwartz and Hongyun Han report another striking indication of continuing progress toward marital equality. Through the 1980s, couples in which the wife had more education than her husband were more likely to divorce than couples in which the wife had less or equal education. But couples who have married since the early 1990s have no added divorce risk when the wife is better educated. In fact, the researchers found hints that such couples may now be less likely to divorce than those in which the husband has more education.

But while the sexes have become more equal, society as a whole has become far less, producing especially deep losses for young men. In 1969, by the time men reached age 25, three-quarters were earning wages that could support a family of four above the poverty line. By 2004, it took until age 30 for the same percentage of men to reach this income level. And while in 1969 only 10 percent of men ages 30 to 35 were still low earners, by 2004 almost a quarter of men in that age range remained low earners.

Rising inequality has changed family dynamics for all socioeconomic groups.

In 1970, marriage rates varied little by level of education, although men and women with only a high school degree were somewhat more likely to marry than those with a college degree. In the 1970s, divorce rates rose sharply for all educational groups. Since then, however, marriage and divorce patterns have diverged.

Among Americans without college degrees, marriage rates have fallen precipitously and divorce rates remain higher. Divorce rates have fallen for college-educated couples, who are now considerably more likely to get married, and stay married, than their less-educated counterparts. According to the sociologist Philip N. Cohen, among 40-somethings with at least a bachelor’s degree, as of 2012, 63 percent of men and 59 percent of women were in their first marriage, compared to just 43 percent of men and 42 percent of women without a bachelor’s degree.