Complex sentence: Nursed in his final moments by a remorseful von Rauffenstein, de Boeldieu laments that their usefulness to society (as aristocrats) will end with this war, and that he pities von Rauffenstein, who will have to find a new purpose in the emerging social order.
Split into simpler sentences: Nursed in his final moments by a remorseful von Rauffenstein, de Boeldieu laments that their usefulness to society (as aristocrats) will end with this war. He also pities von Rauffenstein, who will have to find a new purpose in the emerging social order.