What is Boyne trying to convey when he writes that Bruno commonly sees his mother and Lieutenant Kotler whispering together?

What is Boyne trying to convey when he writes that Bruno commonly sees his mother and Lieutenant Kotler whispering together?

What is Boyne trying to convey when he writes that Bruno commonly sees his mother and Lieutenant Kotler whispering together?
What is Boyne trying to convey when he writes that Bruno commonly sees his mother and Lieutenant Kotler whispering together?