What is the theme in The Persian Pickle Club by Sandra Dallas?

Friendship is the narrative's central thematic concern, in that all its situations, characters and events in some way or another relate to the question of what friendship is, what it means, how it manifests, what it requires, what narrator Queenie Bean thinks it is, means, manifests and requires. In other words, there is some question as to whether her perspective is in fact authorial perspective, whether what Queenie says is what the author intends the reader to believe.