I dated a woman 19 years older than me for a year we did everything together . But maybe I'm wrong of course ;) My sister have boyfriend 4yrs younger than she is , and that's OK for them :) . Been with them and my last was 8 years older.
The social rule defining the youngest age one may date without it being socially multiply by two, and add seven to get the age the older partner would have to be. The relationship becomes appropriate in six years: 2 x (30-27) or 46-40, OR 46 The new meaning is that dating a woman younger than "half your age plus