Not the point. Im sure in Japan, no one talks about it either.
Bottom line is its biology - women are pickier than men. Men can only provide sperm and resources. When women dont need resources, they get pickier - a percentage sharing a small pool of alphas (however defined), another percentage being celibate and so on. the only question is the numbers involved.
I think 20-30% is reasonable.
Look at this:
Granted, it fits two separate explanations.
1) The woman is cohabiting with a male but not married
~AND/OR~
2) The woman was chasing Alpha cock, and she could get him to f**k her, but he would not commit to her (as other women were after him too etc).
I ask that you consider the second one as a very real partial explanation.
As the sex ratios are more or less even - if lots of girls are only going after alphas, non-alphas have a much more limited pool, with many being involuntarily celibate.