Explain the irony of postcards.

The irony of the postcards lies in the fact that neither their mother was right for sending them, nor his father for keeping them secret. They were only sent for the first few days on Emmett’s mother’s road away from them, and their father kept them secret to save them from the pain. It soon becomes apparent that Emmett’s mother suffered from depression, and she left them after spending a happy 4th of July night with her family.