Scenario 1: Kentucky law permits a seventeen (17) year old to have sex with a twenty-one (21) year old, but prohibits them from marrying unless they have permission from a court. Scenario 2: Kentucky law permits a seventeen (17) year old to have sex with a twenty-two (22) year old, but prohibits them from marrying.

Is it OK for a 20 year old to date a 16 year old?

No, its not against the law for a 20 year old to DATE a 16 year old. The definition of date means to go out together to a movie or to dinner or dance. It does not mean having sex regular or oral.