Dear Carolyn: I’d be interested in hearing your take on the age-spread dating rule of not dating anyone younger than half your age plus seven. I know there are exceptions to every rule, but I also know that wherever these truisms come from (and where do they come from?), there is usually some reality and meaning behind them.

If it helps, in this case, the woman is in her 20s and the man in his 40s. The woman is not mature for her age; rather, if anything, the opposite. Haven’t met the man, but he has never been married and has no kids. The woman believes that if two people really love each other, then what does age or age difference matter? I’m trying to be vague so as to not to flavor the question.

Obviously, staying in or getting out of this relationship is a decision that she needs to make. I’m just hoping for some light-shedding. – Curious

My take is that you’re trying to find a number to back you up on your objection to the man your daughter – right? – is dating. It’s like licorice, a tough flavor to conceal.

And to borrow from my favorite philosopher (Finn in “Adventure Time”): “That road you’re on? Leads to nowhere.” The harder you try to make a case against someone’s choice – especially when that someone isn’t entirely mature – the harder you can expect the pushback to be.

If this 20-something is happy, then embrace that and back off.

If this 20-something is not happy, then that’s what you address with her, without using dubious mathematical formulas and without even pinning your concern to the guy. “I’m worried about you – you don’t seem like your usual self.”

You’ll get the best results if you listen to her and respect her autonomy, and the worst results if you preach as if her life would be best lived as you envision it should.