What did you not know about grieving a loss before you went through one?

I am surprised by the peaks and valleys of grieving the loss of my marriage. I thought it would be a fairly steady process through the five stages that Kubler-Ross describes but instead have found that it is much more of a roller-coaster. I can be doing fine and then a ghostly memory will haunt me or a dream of my former life will have me in tears. Is there anything you have learned about loss that could help others?