Elisabeth Kübler-Ross

"The Kübler-Ross Model, commonly known as the The Five Stages Of Grief, was first introduced by Dr. Elisabeth Kübler-Ross in her 1969 book, On Death and Dying.^[1]

Included in the book was a model, The Model of Coping with Dying, which was based on her research and interviews with more than 500 dying patients. It describes, in five discrete stages, a process by which people cope and deal with grief and tragedy, especially when diagnosed with a terminal illness or experience a catastrophic loss. In addition to this, her book brought mainstream awareness to the sensitivity required for better treatment of individuals who are dealing with a fatal disease or illness"

The stages, popularly known in its abbreviated form DABDA, include:^[2]

1. Denial — "I feel fine."; "This can't be happening, not to me."
   Denial is usually only a temporary defense for the individual. This feeling is generally replaced with heightened awareness of possessions and individuals that will be left behind after death.
2. Anger — "Why me? It's not fair!"; "How can this happen to me?"; '"Who is to blame?"
   Once in the second stage, the individual recognizes that denial cannot continue. Because of anger, the person is very difficult to care for due to misplaced feelings of rage and envy. Any individual that symbolizes life or energy is subject to projected resentment and jealousy.
3. Bargaining — "Just let me live to see my children graduate."; "I'll do anything for a few more years."; "I will give my life savings if..."
   The third stage involves the hope that the individual can somehow postpone or delay death. Usually, the negotiation for an extended life is made with a higher power in exchange for a reformed lifestyle. Psychologically, the individual is saying, "I understand I will die, but if I could just have more time..."
4. Depression — "I'm so sad, why bother with anything?"; "I'm going to die... What's the point?"; "I miss my loved one, why go on?"
   During the fourth stage, the dying person begins to understand the certainty of death. Because of this, the individual may become silent, refuse visitors and spend much of the time crying and grieving. This process allows the dying person to disconnect from things of love and affection. It is not recommended to attempt to cheer up an individual who is in this stage. It is an important time for grieving that must be processed.
5. Acceptance — "It's going to be okay."; "I can't fight it, I may as well prepare for it."
   In this last stage, the individual begins to come to terms with his mortality or that of his loved one.

Above is all from Wikipedia

Then some 25 years ago she started to apply it to the grieving.

But losing a loved one is not like having a terminal illness, there is no end point to having lost someone, the loss remains and can cause perpetual sorrow. Yes the initial shock and grief subsides but it can ebb and and flow and you can still be hit by it when least expected.

The idea of getting closure on grief is compelling but is a fantasy, it is fiction to imagine we can love, lose, suffer and then do something to permanently end our sorrow. There is a reason it is called a loss is because that it exactly what it is a loss.

Closure is an appealing concept because that way we can never be surprised and disordered by grief years later.