When people realize they are unable to stop the disease that is destroying body and life, and that they can't continue to bargain, they begin to prepare for final separation from this world. They grieve and mourn for themselves. It is understandable when a widow grieves a year at the loss of a spouse. Dying people must face the reality of losing everything they know and love. Each daily separation points out a final separation.
People become silent, engaging in minimal conversation.
They may begin to limit visitors, dismissing friends one by one until only immediate family or a close loved one is left. To encourage the depressed people to look at the sunny side of things is to ask them to not contemplate impending death. To tell them not to be sad would not be appropriate. All of us are sad when we lose someone we love. Dying people are in the process of losing everything and everyone they love.