How does Boyne show the effect that Bruno's disappearance has on his family in The Boy in the Striped Pajamas?

I think
that the breakup of the family reflects the seismic effect of Bruno's disappearance.  When he
disappears, his mother and sister leave for Berlin, convinced that he would have gone there.
 His father remains at Auschwitz and searches for his son.  In the end, this shows the effect
that Bruno's disappearance has on his family.  They could not progress with their life as if
nothing had happened.  Bruno's role in the family and his absence created such a great hole that
the family experienced fragmentation.  Boyne creates a setting in which Bruno's importance is
accentuated when he disappears.  It is at this moment that the Holocaust has become a
personalized reality for the family, something that the father already knows and recognizes in
his revelation.  

Bruno's absence enables the pain of the world constructed
by the Holocaust to be realized in the most intense of manners.  It is for this reason that his
disappearance has a profound impact on the family at the conclusion of Boyne's work. It is in
this light that the effect of Bruno's disappearance is extremely significant in the narrative.
 When Bruno leaves, the sense of transcendence from the world disappears with it.  The reality
of the world comes crashing down on the family, resulting in the family's scattering apart from
one another.