Virginity is something that has a strange status in modern society. Not too long ago, it was expected that both men and women be virginal until marriage, but gradually that expectation has faded, with the sexual revolution accelerating it. Conservative-minded people tend to believe this was due to fading moral values. I used to agree with this, but am not sure anymore.
I've come to believe that everything is more or less driven by economics. Compare the average man in, say, 1650 to a man today. In 1650, a man spent all day laboring on the farm, glad that the land he tilled was finally his. He married early, at around 13 or 14 years of age, and had children soon afterward. It was ordinary and routine.
Doing something like that now would be considered not only absurd, but pathological. Teenage pregnancy is almost on par with a criminal record in how it ruins your life prospects. Having to work all year on a farm at 13 or 14 instead of going to school would be seen as child labor- a crime. What changed?
It's simple: Technology advanced, making old jobs redundant. Around 100 to 150 years ago, automated machinery started replacing jobs that previously needed a large number of farm hands to perform. The population did not go down; instead, it skyrocketed upward, and large numbers of children found themselves unemployed. This advancement of technology resulted in increased complexity, which required more intelligence and skill. Hence, the public school system was born, and marrying at 13 or 14 soon became history.
Fast forward to the 1940s and 1950s, where housewives found themselves increasingly redundant. In eons past, tanning hides, preparing meals, and washing clothes took all day, and were full-time jobs for a woman. With their children at school all day, and with the advent of factory-manufactured clothing, supermarkets, and washing machines, housewives found themselves with nothing to do, and became restless and upset. Enter feminism, women joining the workforce en masse, and an enormous demand for education.
And now we're in the present. You see what is happening here? Economic forces are coalescing to push the age of marriage farther and farther back. It's getting to the point where many people don't even have a decent job until they are in their early to mid-30s. More and more jobs require increasingly lengthy periods of education beforehand. How can people settle down and marry at some pre-ordained young age in such an environment? It's simply too much to expect of all but the most economically-fortunate people.
It could be argued that in the past, people were better at being chaste until marriage. That has to be put in perspective with the average age of marriage, however. It's much easier to be chaste if you're getting married at age 13 or 14- you've only been a sexual being for a year or two! By your mid-teens, your hormones are in full swing, and you want to have sex. A strong shaming culture can maybe keep the lid on things until you're about 16, but that's when it starts seriously breaking down.
People who are sexually mature need sex. It's not as urgent as food, but it needs to be sated in order for a person to be happy. The old, conservative ways of doing things - imploring people to be virginal for years, or even a decade or more, is unrealistic, callous and almost sadistic. People demanding extended chastitiy are basically stuck in time, not realizing that the train has left the station a long time ago. Their ideas worked in pre-industrial or pre-globalization times. But we live in an industrialized, globalized world of global competition.
People are adapting by engaging in premarital sex, which is also partly enabled by birth control technology. This has its major down sides, up to and including a potentially fatal one - the likely inability to form quality, lasting relationships. But such is the paradox of modernity.