When we are talking of great-great-great-grandmothers, just so you remain on point, we are talking about women who became mothers around 1922 (using a multiple of 18 years of age per generation) or more likely, before 1912 (using a multiple of 20 years of age). Statisitics from that period regarding intimate family issues are scarce; however, it is worth noting that women from that period were regarded as chattel or property of their husbands. Women in the United States only achieved an independent right to vote in 1918; in France this right was conferred in 1944 and in Switzerland in 1971.
From Managing Infidelity: A Cross-Cultural Perspective (1)
By: Jankowiak, William; Nell, M. Diane et al. | Ethnology, Winter 2002
Anthropologists have not systematically examined extramarital affairs. Our cross-cultural study found that within every culture men and women actively resort to mate-guarding tactics to control their mate's extramarital behavior....
Conventional wisdom holds that in many societies women express relative indifference to their spouse's infidelities. Many social-science researchers ascribe this indifference to either male's propensity for psychological violence (Bourdieu 2001; MacKinnon 1988) or women's structural marginality (Freeman 1990; Harris 1993; Leacock 1993; Ressner 1987; Rosaldo and Lamphere 1974). These theories link patriarchy with male superiority to account for institutionalizing a double standard. A constant life lesson for women in these societies is their inability to forestall their spouse's infidelities. Reinforced by folk ideology, social convention, and common practices, men come to believe that it is their right to have extramarital affairs, while women become indifferent to their spouse's infidelity.
From : Premarital Sex
To my point that widespread infidelity or parity with men in infidelity by women is not an historic, but rather a contemporary phenomenon that trended sharply upward with the distribution of birth control to the unmarried legalized in the early 70s (Eisenstadt v. Baird, 1972), combined with the so-called Sexual Revolution beginning in the late 60s, "At the beginning of the century, very few women were sexually active before marriage. By the end of the century, most of them were."
From: Extramarital Sex
The following chart shows a researched disparity in rates of extramarital sex between men and women, compiled in the more recent era of statistical study:
To my point that rates of infidelity by men are higher than those by women, even as late as 1992 there was a measurable difference: "According to the 1992 National Health and Social Life Survey, the most authoritative study of American sexual practices, 'Over 90 percent of the women and over 75 percent of the men in every cohort report fidelity within their marriage, over its entirety.' ”
Additional overview from Wikipedia about the cross-cultural issues associated with Adultery re-emphasizes the greater social penalties for women than for men of infidelity.
And finally, may I respectfully point out that both Chaucer and Shakespeare were writing entertainment literature, not social science literature; there is no way to determine how much of their story-telling was based on truth, but rather on wishful thinking. Surely you have heard that women and women's points of view were greatly underrepresented, with the rise of women in literature coming hundreds of years later with Eliot, the Brontes, etc.
The male artists and writers of Chaucer and Shakespeare's days 500+ years ago typically associated with a bawdy class of women in the cities and drinking establishments their own celebrity afforded them. But the great bulk of women in the traditional Christendom of pre-World War I Scotland, England, and the United States lived in small towns or rural communities where their actions were subject to the scrutiny and moral judgment of their neighbors. I do have to work today, so I'm not going to cite it; but I recall from previous research that the numbers of people living in cities and towns vs. rural communites, while occuring somewhat earlier in Scotland due to its leading role in the Industrial Revolution (and the Highland Clearances that pushed Scots into cities and the U.S.) only became a majority in the U.S. in 1939.