The idea that a person simply does not exist anymore does not follow the rules the brain has learned over a lifetime. Furniture does not magically disappear. If the person we love is missing, then our brain assumes they are somewhere else and will be found later. The action required in response to their absence is quite simple: Go look for the person, cry out, text, call, or use any possible means to get their attention. The idea that the person is simply no longer in this dimensional world is not a logical answer to their absence, as far as the brain is concerned.
