Back when most women didn't work and were housewives, if a woman became a single mother it would be a serious consequence on survival for the mother and the child. That all changed in the space of 2 decades because of higher economic status for women and contraception. Once more and more women started working, they were no longer as dependent on men as a provider. A safe contraceptive pill and safe condoms meant women were also now able to have sex outside of marriage and afford to have more fun. This change although liberating for women, was really bad news for any girl that wanted to settle down. The existence of freer women weakened the bargaining power of all women in general by a lot. I'll explain this more in part 4, when we look at game theory.
Whilst most women in developed countries want to marry later these days and get a career. The change in sexual attitudes since the 1960's meant men could marry even later! Men used to marry in their early 20's because well, if you find a nice girl then you settle down. Now men can have sex outside of marriage there's less incentive to marry. Guys don't need to worry about marriage, feeling they can get all they want from a playboy lifestyle. Other's delay marriage till middle age. Lesson from this? We guys don't really need to worry, we got a lot more time and as I will explain in part 4 bargaining power than girls in big cities. Girls, if you want a higher chance of finding a guy that will settle down with you should find an older guy that's played enough.
If you find a guy who's 24-25 when you're 22-23, and you date 5-7 years and the guy still is not ready to settle down then you're in a pretty tough situation, because you're approaching 30 and the guy still wants to play for 3-5 more years..... I would advise finding guys at least 5 years older in today's society, and if you're looking to date 2-3 years and get marrried, then the guy better be close to 30 or older when you meet him. This is not a fixed rule since some guys never want to settle down, whilst others want to settle down sooner. Picking older guys is about increasing your own odds.