Reminder girls will fuck complete strangers the day they meet, yet withhold sex when they actually get into a relationship
Why do you believe this to be true about all women?
Yes, it's based on what I've seen so far. But you should know all women are like that.
It sounds like you are being misogynistic. Women are not immoral because there are differences across the board. People can choose when they want to have sex and that is their choice.
I know I'm not the first person to notice this, but it is well worth mentioning.
You may have had some frustrations in your relationships, but this does not mean that all women do that. I hope that you can find better relationships in the future.