Based on the oft-quoted minimum-socially-acceptable-age-of-a-partner formula, which is half your age plus 7 years, I have provided, below, a table of said ages.
So, when you’re out and about with your favorite WL, if she is below the tabulated age you should introduce her as your “niece”. For example: ‘Yes, waiter, I’ll have a Knee Trembler with a twist of lemon and my “niece” will have a Champagne Cosmopolitan.’
If your consort is over the acceptable age, hold your head high and proceed with