There was a time sex outside marriage was considered evil. That simple assumption solved all contradiction . Women were either saints or sinners .

When sex outside marriage stop being a sin, the morality of sex is debatable ( and what follows can be applied to men too)

There are women who have sex for money , they're called prostitutes and are considered criminals in most countries. Somehow government thinks that doing manual or intellectual work for money is perfectly legal, but using money for the same goal is not.

There are women who use use sex to find husband and start a family. These " pragmatic women " have sex with a smaller number of men but nonetheless use sex to achieve their goal.

Prostitution is legal in many countries, but paying for a date is okay but marrying someone for his income is not only okay but advised by the parents

There are " party girls" who use sex not only for money but just to have fun .

Somehow society has decided using sex for fun is perfectly normal, but using it to find a husband is also normal, but using it to make money is not .

It's perfectly legal for a woman to have a child at 60 but a single woman of 25 is not allowed to adopt a child

Polygamy is considered immoral but Abraham and other biblical prophets have multiple wives and so the founder of Islam, and they're very considered moral people infact the source of morality

Sex with an underage person is legal if you're underage too, which is like saying it's okay to rob a bank if you're a banker .

Set of Morality is always conflicting each other. We live under the moral shadow too much. And it's so hard to live under the moral shadow if we want to be truthful to ourselves..
I don't hide under a moral shadow. on Sex you can have it all you want as long as you are certain that you won't regret it. And the other partner you are having it with is not regretting it.