Dear Carolyn: My parents, married for 30 years and now divorced for 15, last saw each other intentionally at my wedding 14 years ago.

They still live in the same town, and ran into each other at the theater several years back. Whereupon, from both accounts, my dad willfully ignored my mom in the lobby as she tried to greet him. His version is that he will not be berated into talking to her. And he hasn't!

I've accepted this and see it as generally out of my control. While the fact that my brother and I are geographically dispersed also heavily contributes, my parents have never shared a holiday, grandchild event, etc. My dad is a hard person to be emotionally close to, but he does try in his way to be a parent and grandparent. My mom has a much stronger relationship with her kids and grandkids.

But! The bar and bat mitzvahs of their grandchildren are approaching. I recently received the date for my son's bar mitzvah, for 2022, and shared it with extended family.

I reminded him of a decision I made years ago after the theater incident: Civility is the price of admission. I want him there and my son does, too, but I will not host a momentous event where my father willfully ignores my mother. I told my dad he was welcome if he demonstrated his ability to be civil to my mom before the event.

He has declined, specifically and in writing, to do this and asked if he can still come.

I feel both strong in my conviction to say no to his attendance given the circumstances, and heartbroken over doing it. Am I missing some angle here?

— Stuck in the Middle

Stuck in the Middle: You have every right to insist on civility.

You have cause to want some assurance beforehand that your parents can pull this off. Fifteen years and he won’t say “hello”? That’s the hill he wants to die on? Clearly the wrong person is feeling bad here.

You also have wiggle room, though, if you really want it: Hostile disengagement is less volatile than hostile engagement. If your mom is happy to ignore him right back — big if — then they could conceivably attend without interacting and without dragging the party down with them. Suspenseful for you, obviously, so choose that stress only if exclusion stress feels worse.

I’d balk at rewarding Dad’s sour intransigence, for sure. But to make decisions solely on rewards and punishment risks a nose-dive to your dad’s “You can’t make me!” level of emotional functioning.

So here’s something to consider: The standard you’re asking him to meet — “to demonstrate his ability to be civil to my mom” — is vague, and 2022 isn’t soon. Why not invite both parents to every non-“momentous” occasion until then? Some even held in their town? Tell your dad they’re all low-stakes practice runs for the many, bigger grandkid occasions to come; he can attend all or some or none, his choice, of course. But you hope he’ll choose one soon to get it over with.

Meantime, decide not to decide yet on the bar mitzvah. See what your dad does with two years to grasp what he stands to lose. See whose certainty solidifies, softens or breaks.

Write to Carolyn Hax at tellme@washpost.com. Get her column delivered to your inbox each morning at wapo.st/haxpost.