Why do you think Bruno's mother fails to tell her son the exact nature of his father and Job?

Bruno's mother likely fails to explain the exact nature of his father's job and the family's situation because she wants to protect him from the harsh realities of their lives during a time of war and persecution. She may also be trying to shield herself from the uncomfortable truths that come with acknowledging the moral implications of her husband's role in the Holocaust. Additionally, by maintaining a facade of normalcy, she hopes to preserve Bruno's innocence for as long as possible.