Sex and morality has been a huge part of society for many generations. But as society has grown, old morals such as single, unmarried woman having sex before marriage, women being sexually aggressive and the such have fallen like gigantic trees being felled in the forest. Victorian-era type standards are long since gone...society has evolved and moved on. Old morals in our society usually fall because there always is an effort to change things by the generations in the respective eras. Generations before start the process, and the cudgel is passed onto a new generation who start having a bit more liberality in sexual attitudes and morals, so on and so on until there is total sexual liberation and morality.
During the 1960's and '70's, came the birth control pill and women's liberation, which helped evolve sexuality from a forbidden term to something that could be enjoyed by women-without the connotations of being some kind of 'slut'. With the threat of pregnancy removed through the pill, women could explore their sexuality far more than their mothers or grandmothers could even dream of. The sexual revolution of that era freed men and women alike of that generation into a whole new world.
With a relaxation in movie censorship in that time period, movies could finally show scenes that had overt nudity and sexuality, something that was just briefly touched on in the pre-Hayes censorship code era. Now movies and TV were joining the mainstream of a much changed world, showing a realistic world of sex that not only portrayed the glories of freer sexuality, but some of its darker side such as teen-age pregnancies, unwed mothers and the such that was part and parcel of the era and the generation watching it. Such concepts are now very easily mainstream and nothing near so taboo to talk about, as evidenced by the recent news stories of the group of teen-age girls who took a group pact to become pregnant and help take care of each other's babies.
As new phenomenon of sexuality's darker side became apparent in the 1990's and beyond of date-rape, incest, children having sex (and sometimes impregnating or getting pregnant by adults) started to be portrayed on TV and movies. These venues reflected the reality of what was going on in the world-and was no longer being hidden or talked about in covert corners. Although sex and morality had evolved, some more negative aspects of sexuality were still considered abhorrent and repugnant even by a more evolved and enlightened society. Even a populance that had become so tolerant to a looser standard of sexuality and morality knew that there were some lines never to be crossed.
Generations who never knew the repressive sexual morays basically still retained somewhat a strong moral core, that had been passed from one generation to another in an evolving society. A society that was far more tolerant, but still was in some ways the same as generations before. But instead of shunning unwed mothers, it now shunned the moral evils of a new generation, a new era.
But at least this time, they were true evils. But some aspects of popular culture seemed to have almost a morbid fascination with some of these more heinous aspects, including the case of former schoolteacher, Mary Kay Letourneau having sex (and becoming pregnant with her very young student). Such cases of female teachers becoming pregnant, or just having sex with underage students seemed to almost draw a psycho-sexual fascination with some. Additionally, there seemed to be some tacit sympathy towards the plight of these teachers and the students they molested, nowhere near acceptance, but maybe some understanding from a more evolved society.
By the time the 1980's dawned, homosexuals and lesbians, once considered 'degenerates' and 'perverts' were celebrating a rebirth in modern society, thanks in part to a new generation of 'baby-boomers', who had overturned some significant aspects of the old order. AIDS started becoming epidemic, causing several years of fear that the virus could be spread with ease from the gay community into the heterosexual community. After it was conclusively proven that the virus was only spread through 'unprotected' sex and 'dirty' needles, fears eased and the moral backlash against homosexuals started to ease by the 1990's. Again, society evolved into accepting homosexuals much more. Moral standards and prohibitions against gays that had briefly flared up during the height of the AIDS crisis eased somewhat.
Sexuality and morality will always be there, but will continue to change somewhat to reflect new times and thinking. At times, it may go back and forth, but will never retreat to more oppressive times and standards. The core of society will always grow and develop, and so will sexuality and morality.