This rule is not set in stone. It just measures what age gaps are seen as socially acceptable. If you are happy, its perfectly okay to date someone a couple of years younger or a couple of years older than your recommended age gap. As long as its legal, someone 18 or years older should not attempt to date a minor.

How do you know if a younger man is in love with an older woman?

This is a very obvious tell. If a younger man is into an older woman, hell make a show of his virility by changing the way he stands. Hell angle his pelvis directly at her in a strong display of his intense desire. He wants to make it clear hes not just looking for friendship.