Boundaries got a reputation as walls, which is unfortunate, because in practice they look more like a house rule: nobody raises work after nine.
They are usually negotiated after something goes wrong. A holiday ruined by one person's family, a conversation that went too far, and then a quiet agreement about how that will not happen again.
The healthy part isn't the rule. It is that both people were allowed to ask for one, and neither treated the asking as an accusation.
If there is a rule you have been enforcing silently and alone, it might be worth saying out loud.