Of course it's all about us! It is a very uncommon person, if there is indeed anyone at all, who isn't thinking of themselves- consciously or subconsciously- when they grieve. It may be masked as "oh but he/she was so young", "she suffered so", "what about his family", but in each and every one of those cases it's our psyche projecting what this person's death means to him or her. We put ourselves in the deceased's shoes, or the family's shoes. None of this is conscious. Something that this person provided to us - to our ego- is lost. Naturally we are sad, an important part of our life is gone. But the root cause of sadness is the loss of what this person did for us, for our ego.
It sounds pretty awful when put in those terms and this is just one explanation of grief from a psychological standpoint. Other philosophies have their rationales- Eastern ways of thinking might explain it by blaming our "attachment" to the person, when in reality everything and everyone is impermanent and attachments only bring pain and suffering.
It's not that difficult to understand these ideas in intellectual terms but the raw, gut-aching feeling of grief is very real. Oftentimes our bodies have physical reactions to profound grief; nausea, lack of appetite, insomnia, depression, irritability, restlessness. The mind and body are inextricably connected. Animals have been noted to grieve the death of a mate by exhibiting the same symptoms that humans do.
Grief serves a cultural purpose as well as a psychological one and is our way of healing. There are many rituals to give the hands and mind something to "do", to keep one in motion. Services to be planned and and attended; small and large tasks occupy the most difficult first few days and weeks. Does one ever get accustomed to the loss? Surely it changes over time, but there is always that hole in the heart, in the ego, and the person.
Grief is not rational. Understanding the root causes does not make it go away. Being able to say goodbye to the person does not magically give one a "get out of grief free" card. It's a gauntlet that must always be walked and there is no feeling better - not the correct word, perhaps 'at peace' with the loss is more appropriate- until the process is experienced. It's never completed but is an initial stone in the pond that creates ripples throughout the rest of a person's life. Sometimes large, sometimes small, but always there.
I know you lived your life well, Sandy, and were at peace with your death. You had and gave the gift of knowing it approached and were able to say goodbye, to receive others' goodbyes. I truly believe your soul had completed its purpose and you were ready. That doesn't mean I'm not going to miss you, my ego be damned, and there will always be a place in my heart for you and the others who have gone before and those who will go after. Deep peace to you, my friend. That's the best I can wish for.