Modern Orthodox premarital sex

https://www.jewishideas.org/article/its-all-relative-contemporary-orthodox-jewish-family-america-0

In their mid-1980s study of varieties of Orthodox Jews, sociologists Samuel C. Heilman and Steven M. Cohen (Cosmopolitans and Parochials: Modern Orthodox Jews in America, Chicago: University of Chicago Press, 1989, pp. 173–179) found, across the range of Orthodox people they studied, “younger respondents consistently reported more indulgent attitudes toward the practice of premarital sex than their older counterparts”; that almost a quarter of those they labeled as “centrists” (not to be confused with what scholars at Yeshiva University term “centrist”; see David Berger’s highly critical review of the Heilman-Cohen book, Modern Judaism 11:2, (May 1991), pp. 261–272) do not disapprove of sexual relations between couples who are dating seriously, and as many as 40 percent do not disapprove for those who are engaged to be married; and that among younger centrists, only about half disapproved sexual relations for those dating seriously, and less than half disapproved for engaged couples. Although these figures reflect attitudes, it is hard to imagine that there was a highly significant gap between attitudes and behavior. The popularity of the expression “tefilin date” also apparently reflected a reality of otherwise observant Orthodox Jews who spent the night with their dates but prayed wearing tefilin the following morning. 

Most recently, Zvi Zohar (“Zugiyut al-pi haHalakha lelo hupa veKidushin,” Akdamot 17 (Shevat 5767), pp. 11–33) argued, based on the opinions of Nahmanides (1194–1270), Rabbi Abraham ben David (Rabad, 1125–1198), and Rabbi Shelomo ben Aderet (Rashba, 1235–1310), as well Rabbi Jacob Emden (1697–1776) that there is no prohibition against sexual relations without marriage so long as the relationship is not illicit, that is, it is consensual and monogamous, and the woman observes the laws of niddah and mikvah. His thesis was strongly rejected (in the same issue of Akdamot) by Rabbi Yehuda Herzl Henkin, Shemuel Ariel, Mikhal Tikochinsky, and Rachel Shprecher Frankel. Despite their rejections of its halakhic legitimacy, sexual relations among the unmarried was apparently perceived to be significant enough of a phenomenon in the Orthodox and traditional communities that the Ashkenazi Chief Rabbi, Yonah Metzger, issued a ban on allowing unmarried women to use mikvaot. The effectiveness of that ban is anyone’s guess.