Do not make a child responsible for keeping the adults around them comfortable.

Children read a room faster than anyone gives them credit for. When the atmosphere depends on their mood, an unhappy child learns to hide being unhappy, and a worried one learns to be reassuring. It is rarely asked for out loud; it comes through sighs, tension, and the relief when they behave. What gets built is a person who monitors everyone else before checking on themselves.

Watch for the child who is always fine, and make it clear that they are allowed not to be. Say plainly that the adult things are not theirs to manage. Then handle your own difficulty somewhere they cannot see it.