The answer is: she misinterprets the reactions of others.
The aunt, accompanied by three small kids - her nephew and two nieces - is riding the train on the same carriage as the bachelor. While observing the man, she decides in her mind that he is hard and unsympathetic due to his scowling.
The aunt is judging the bachelor’s reaction and, at the same time, she is afraid that he might be judging her and the children. She’s concerned that the man thinks her nephew and nieces are impolite children and that their aunt doesn’t educate them properly.
The bachelor is, however, merely astounded by her inefficiency when it comes to answering the children’s constant questions about everything they see in an interesting enough way to keep them quiet and focused.
When he finally voices his opinion, the aunt invites him to tell the children a story, which she has just tried to do, but unsuccessfully. He does so and is deeply appreciated by the children, for his story does not intend to teach them some moral lesson – like the aunt’s did- but only to keep them entertained.
