Where in the book boy in striped pajamas does it give proof that brunos mother is having a affair?

In "The Boy in the Striped Pajamas," there is no explicit proof that Bruno's mother is having an affair. However, subtle hints suggest tension in her marriage, particularly in her conversations with Bruno and her demeanor when discussing the family's move. Her discomfort and the way she reacts to her husband's authoritarian behavior imply that she may be emotionally distant or unhappy, which can lead to interpretations of infidelity, though it is never directly stated in the text.