What does 5-5-5 refer to in the book? no

The story, as
well as Susie's issue in the story is watching these three persons (her mom, her Dad, and her
sister) go through the 5 stages of grief which are: denial, anger, bargaining, depression, and
acceptance. Each of the three had their own way to go through the process, and none of them did
it neither similarly nor in order. One's process affected the other's. It was a triangulation
and a continuum that did not seem to have a final end the way that it says that the 5 steps of
the process end.

Throughout the novel, Susie experience the grieving process
with them, and tries to help each of the three the best way she can from her
heaven.