In what sense are the three opening paragraphs of chapter seven an example of irony?

The irony in the first three paragraphs is that everyone had saved every penny they could earn in order to give the couple a wedding (Jurgis and Ona). Unfortunately, when the wedding was over, they were in more debt than ever. What should have been the happiest of days ended with stress and despair. The following morning, it was work as usual.