There are three sets of dating norms out there for men and women.

Ancient - No Sex Until Marriage

Was widespread until about 1970, now exists only in conservative religious communities / countries. In this dating norm, women would vet men for having "good intentions." A woman who slept with a man who didn't intend to marry her would be slut shamed. Some people still had sex before marriage, but cohabitation before marriage was extremely uncommon. Sex was viewed as being primarily about reproduction.

This dating norm was adaptive in an environment with no effective contraception. Continues to be defended by religious conservatives.

Edit: someone suggested the name "Victorian" for this instead, which I like. And pick 1960 or 1950 instead of 1970 as the end point if you prefer. I'm talking about before the sexual revolution.

Classic - Serial Monogamy

Widespread from about 1970 to the present. In this dating norm, people go on dates with one perspective partner at a time. The man tries to escalate things physically and the couple has sex when the woman is "ready". Both partners can assume the relationship is monogamous without explicit discussion. As the relationship progresses, the couple will cohabit first and then get married. A woman who sleeps with a man that isn't interested in a relationship is slut shamed. One night stands still happen, but sex outside of a monogamous relationship is uncommon. Sex is viewed as being primarily about connection with your partner.

This dating norm continues to be adaptive as it leads to people getting into relationships, which are beneficial for most people. However, it is very rarely defended (or even described!) in the abstract. This leads to confusion for socially clueless men, as they do not realize women expect them to escalate things physically.

Modern - Hook Up Culture

Widespread from about 2000 (?) to the present. The biggest difference vs the Classic dating norm is that the expectation of monogamy is dropped. When I google "dating norms" the first link I get advises women to date multiple people at once. In this dating norm, the man and woman have sex ("hook up") from the beginning, outside a monogamous relationship, and it later becomes monogamous only through some explicit mutual agreement. After that, things progress as in the Classic norm. Slut shaming is taboo. Sex is viewed as being primarily about pleasure.

The strange thing about modern society is that only religious conservatives will criticize Hook Up Culture. There is almost no defense of Serial Monogamy from a modern secular perspective, even though many people probably "agree" with it on some level. Interested in people's thoughts on this.