Some time ago (I think about 5 years, but it can be a different term, but not too long), the Earth was hit with some Mind Control impulse (or radiation, or whatever else to call it), which made all (adult, or legal-to-write-about) women see themselves as free use and lose most of sexual inhibitions (no scat, gore, violence, although some pain play can be ok). Add bisexuality, and a taste for physical punishment (spanking, whipping, etc), exhibitionism.
Additionally, same MC made women very proactive and even aggressive in 'protecting and promoting' their new 'rights' - so they launched a crusade against social institutes and groups that stood for traditional or conservative values.
Laws got changed, allowing public nudity and sex. Lots of infrastructural changes, like, any changing rooms completely removed, toilets or showers becoming uni-sex, as well as any living facilities (college dorms, plus legal aspects, like hotels don't even need to ask woman when giving her a room with a guy - they never mind), I'd add a great number of newly build public showers/baths (all that fucking makes people sweaty and covered with juices, which, while not in any way offensive, sometimes are irritating - and of course, such showers had glass walls into public areas), etc.
While total female nudity is not a common thing (still need to protect from weather, or pockets to carry stuff), but women had no objections from getting naked on smallest reason, or with no reason at all.
Orgies, weird sex contests, sex related activities (like female sex tourism) became a common thing.
As a bit of unexpected social change, the advance on corporate ladder became pure skill and character - no pretty face could buy a position anymore, plus being total free use sluts didn't interfere with other social skills - and still allowed a woman to be a strong and strict manager or worker. On the other hand, many women started seeking employment in companies that usually had more men (looking for you-know-what at the workplace), resulting that most jobs by the end of this period had strong 50-50 men-women population.
Women became if not maniacally obsessed, then at least strongly concerned about their appearance, and fitness and good grooming became extremely popular (add plastic surgery at your own will, but I'm somewhat against it, at least in mass. But a lady might go for a boobjob if asked for it, or, probably, her contract required it).
Many industries took a hit, or got seriously changed - clothes (having a lot less demand), beauty industry, housing (some women sold their homes and lived roving lifestyle, dwelling with whatever guy let them in.
You can add any other social changes, of course.
But then that Mind-controlling radiation stopped. And women returned to the state of mind they had before it all started.
And this is the point where the story starts, preferably with female PoV. The Main Hero has to deal with a drawer with no underwear and most clothes not covering much (probably only jacket tops left), with a company calendar with her face and all naughty bits on every male co-worker's table, her 'home' porn all over the internet and her own social network profile, with memories of bukkakke party for her birthday, her signature on corporate contract for chairs with build-in dildos or demand for more strict implemention of physical punishment for women... anything like that. Someone, who lived the free use lifestyle to the fullest, but now is no more. And all other women in this world as well.
Like post-apocalipse, but post-mind control free use.
Why five years, as a period for that? I think it is enough for all social changes take their place and become normal, a new generation of people coming into life and taking offices, some new habbits and experiences taking place. Women, after the Mind control ended retain full memory of what they had been doing and how they felt (absolutely great!), but while they were under the influence of MC, their real personalities didn't change much (only not sex-related parts, willpower to go to gym and healthy eating would remain, as any working skills).
How will the 'awakening' feel and how they live through it? How they deal with all new 'hard' changes (oops, no changing stalls in clothes stores, oops, gym showers are unisex, oops, 2 of 3 clothes stores in the city got closed, and the collection in the remaining is a bit extreme by 6 years old standarts).
How do they deal with the question "this madness happened once, it can happen again"?