It's hard to find hard data on it, but in my personal life 10 years ago I experienced women having sex with me only after they felt that they know enough about me and trust me in having a long term relationship, and after the first sex I didn't feel that I still have to prove myself and court, but rather I can focus on having a great time and great relationship with the woman I am with.

Nowdays women have sex with me much earlier in the courtship (generally second date), but they still play hard to get and give a masculine vibe, like they were just brushing their teeth. I can't really blame women doing it, as the high budget movies are portraying the same masculine characters in beutiful female bodies.

Another example that I can provide that I see nowdays is that I was trying to date women in my age range (40), and they are feminine, great to talk to, mature, want to have kids, and talk about being so desparate that they are thinking about just asking a friend to make baby with them to raise up solo, which they know is really really hard. I have a great time talking to them, I just more see them as friends than people I would like to have relationship with.