Different emotions are triggered when we know that death is imminent versus when it comes "out of the blue." Knowing ahead of time that a person is dying allows us to prepare, both by planning ways to minimize the negative impact of the loss after it occurs, as well as saying goodbye. An unexpected death can be much harder to deal with than an expected one. Because survivors haven't said goodbye or resolved lingering relationship issues, feelings of guilt and anger can linger for many years and prevent closure.
The perceived "fairness" of the loss is also important. Losses that challenge our view of the world as a predictable and fair place are harder to manage. For example, it is easier to accept the loss of an aged parent who has lived a full life than it is to accept the loss of a young child. Death from a chronic disease tends to be easier to accept than death by a random, senseless accident or sudden medical crisis that comes out of the blue. Dealing with the suicide of a loved one typically brings about feelings of anger, as well as guilt and regret for not recognizing signs of depression, hopelessness, or other warning signs of suicidal behavior.
There are many ways that people can handle their grief, anger and other emotions. Please read our article on Grief and Bereavement Issues for an extensive discussion on how people can work through the stages and emotions of grief in healthy and productive ways. This article also discusses ways to recognize when grief is becoming pathological and when grief is beginning to come to an end.