They truly mourn that mourn without a witness.

Grief does not perform well. Much of the deepest of it happens with nobody watching: in the car, at the sink, at four in the morning, long after the visits have stopped. Quiet in company is not proof that someone has moved on.

If you are the one grieving, you owe nobody a display, and you also do not have to carry it entirely alone. If someone you know has lost a person, check in a month or two after the funeral, not only in the first week. That is often when the witnesses have gone and the weight is heaviest.