This is a critical moment in the story as it marks a transition from what we expect to be a happy story focussing on the love of Mary Maloney for her husband to something much more interesting. Reading the text carefully tells us that normally on a Thursday night they go out to dinner, which is why Mary Maloney has not prepared anything for her husband to eat. However, even when she says that she could prepare something quickly for him if that is what he would like, he says that he is not hungry at all and asks her to sit down. Note how the narrator describes her feelings:
It wan't till then that she began to get frightened.
Of course, this is when he decides to tell her about his decision to leave her at this particular moment, even though she is pregnant. Thus the mood of the story changes suddenly and we see Mary Maloney for the first time getting scared.