I'm writing this from Vietnam, here they have a culture that does not lie to women. Young Vietnamese women who are 27, 28 and still single are pressured to pick a guy, get married and get on with life.
The reason is because attractive men who are 30+ years of age who are financially successful, reasonably good looking and in shape are statistically rare and want to date and start families with younger women. They are not interested in women their own age because over 35, it becomes a geriatric pregnancy.
The reality is that women should start having children in their 20's and finish up with their family in their 30's with men who are in their 20's to 30's ideally:
A woman’s age is the most important factor affecting her fertility and her chance of having a baby. The chance of having a child is much higher for women younger than 35 years and men younger than 40 years than for older women and men.
*source (aka not my opinion)
This is something women over 30 in America come surprised to find out as they experience for the first time the inability to lock down a guy they like (men will still sleep with you, though as I talked about in "how to tell if a guy likes you").
The dynamic switches
Women have sex with who they want as it's said, men have sex with who they can get. The power dynamic switches and women who hold out too long struggle to find an acceptable man (because let's be honest, a lot of men today are mediocre) to pair bond with:
Women at 18: Hot girl summer!!!
Women at 21: My body, my choice!!!
Women at 25: I'm an independent boss babe!!!
Women at 30: I REFUSE TO SETTLE!!!
Women at 35: Where are all the good men?!?!
Women at 40: THIS IS ALL MEN'S FAULT!!!
Women at 45: I'm still hot!!!
Women at 50: Why won't men my age marry me?! They only want girls under 27! They must be ped0s!
Women at 50+: Why am I invisible?! We need to change beauty norms!!
Girls like men, not boys
This will come as a surprise to any young man reading this but younger women like older men. Not grandpas, just men who have it together in all the ways a woman wants and needs in a man (physicality, presence, ambition, confidence, success, good looks and charm).
I know I personally got way more attention in my 30s from attractive 20 something year old girls than I ever did as a twenty something myself.
A common mistake both genders make is to apply how you think and feel to the opposite sex. We're not the same and have different roles to play and look for different things. Men your peak is 28-36, girls it looks like it's more 20-28.
It takes men longer to become attractive on average
It just takes a guy a lot longer to obtain the things women want, need and find attractive in a man. Style, wealth, status, a good network, physical fitness, social skills and so forth. Unlike girls who are born with what men want which is youth, beauty, fertility and femininity (and no we really, truly don't care about your career or ambition - it's not an attraction signal to us).
This is not to say men want to date a 16 year old or something crazy like that (the common retort I get from saying men like younger women). A man would just prefer to date a 25 year old over a 35 year old any day of the week.
Again, once I hit my 30's I was finally able to date beautiful 20 somethings. Even now in my late 30's approaching 40 I'm still going out with girls who are literally 10-20 years younger than me:
She was university student, worked part time as a yoga teacher and yes, she's stunningly beautiful as is a lot of girls in Vietnam and yes she just wanted a casual FWB relationship with me. Not every girl is looking for their prince charming as the Jordan Peterson types assume.