New types of relationships formed; it was possible for people to live together without marrying and without children.
Information about human sexuality grew, and with it an acceptance of all types of sexual orientations is becoming more common.
Cars extended the range of dating as well as enabled back-seat sexual exploration.
In the mid-twentieth century, the advent of birth control as well as safer procedures for abortion changed the equation considerably, and there was less pressure to marry as a means for satisfying sexual urges.
While pair-bonds of varying forms were recognized by most societies as acceptable social arrangements, marriage was reserved for heterosexual pairings and had a transactional nature, where wives were in many cases a form of property being exchanged between father and husband, and who would have to serve the function of reproduction.
Women eventually won the right to vote in many countries and own property and receive equal treatment by the law, and these changes had profound impacts on the relationships between men and women. In many societies, individuals could decide—on their own—whether they should marry, whom they should marry, and when they should marry.
A few centuries ago, dating was sometimes described as a "courtship ritual where young women entertained gentleman callers, usually in the home, under the watchful eye of a chaperone," but increasingly, in many Western countries, it became a self-initiated activity with two young people going out as a couple in public together.
These people will have dates on a regular basis, and they may or may not be having sexual relations.
This period of courtship is sometimes seen as a precursor to engagement or marriage.