Why did Elie tell Rabbi Eliahu that he didn't see his son?

Elie told Rabbi Eliahu that he didn't see his son to spare the rabbi's feelings and provide him with a sense of hope. The rabbi was searching for his son, who had abandoned him during the march, and Elie did not want to reveal the painful truth about the son's betrayal. By withholding this information, Elie aimed to protect the rabbi from despair in a time of immense suffering and loss.