What Is the Irony in "Federigo's Falcon?"

Monna's son is infatuated by the falcon, and when he falls ill, he tells her, "if you can arrange for me to have Federigo's falcon, I think I would get well quickly." She travels to Federigo's house to request the bird. When she arrives, he decides to cook for her. Seeing as how he doesn't have any food in his house, Federigo kills the falcon, even though he loves the bird, and feeds it to Monna. Her son ends up passing away, and she marries Federigo.