Thirties curve 

As males hit there thirties life gets better they suddenly are able to secure women that previously would have been outside there league factors contributing to this curve are:
Job security and higher income, stability in life and males are yet to peak in physical appearance, all the attributes women look for and when wanting a partner.
Women on the other hand are negatively affected by the age curve, their looks are fading, the biological clock is running out of time and men are looking past them to the younger more desirable versions

My husband is having an affair with a younger more attractive women, he said it wasn't his fault it's the thirties curve

Thirties curve by The true love machine March 4, 2016