In The Glass Menagerie, abandonment refers to a member of the family abandoning the family unit, and leaving others behind to fend for themselves. The play deals a little with the moral implications of such an act, as well as the aftermath. It suggests that such an act may be learned from parents, as the son chooses to abandon the family the same way the father did.
Because of the nature of son to follow father, Tom cannot be held responsible for following in his father's footsteps and abandoning his family.
The Glass Menagerie fails to provide adequate reasoning to explain Tom's sudden departure from the family.