Here's a hypothetical & somewhat over-dramatized scenario loosely based on a real-life issue that arose for a friend of mine this past week:
Person A and Person B have been dating for about a year.
Person A is part of a network of pansexual, kinky, totally-out-of-the-closet poly folks. Person B is one half of a heterosexual couple who opened their marriage not long before Person A entered the picture. Person B's primary partner is introverted, somewhat conservative, and plans to stay in the poly closet indefinitely.
So A and B have weekly dates but do not interact much socially, or hang out with each other's families, other than a couple of perfunctory "let me introduce you to my important people" meetings.
Then Person B's child and Person A's child end up registering for the same summer camp, quite by chance.
Person B figures out the coincidence and asks their in-the-closet spouse, "Hey, can I tell our kid that Person A's kid will be at camp too?
The spouse says no, fearing that this piece of information will lead to a conversation about just who Person A is, anyway, which would totally open that closet door.
Person A, who would like to tell their kid that Person B's kid will be at the same summer camp, now feels duty-bound to respect the wishes of Person B's spouse. So even though Person A feels weird about this level of secrecy, they don't say anything to their kid either.
The two kids head off to their 3-week summer camp, each unaware of the existence of the other. Can you guess what happens next?