Slaughterhouse Five section IV (part I)

Vonnegut brings up death many times throughout Slaughterhouse Five. However, death is talked about nonchalantly. The phrase "so it goes" appears repeatedly throughout the entirety of the novel, which emphasizes the nonchalant way Vonnegut speaks of death. I think the most surprising time Vonnegut disregard death was with Valencia's death. Most people would think the death of his wife would be a devastating event, but Billy is not even phased by the news. Of course, Billy was also severely injured. I find it odd that Billy never seems to have the will to keep on living. For example, when Billy is in the hospital he says, "'You guys go on without me (p.184).'" This is in reference to one of Billy's moments  during the war when he tells the three musketeers to leave him and let him die. Just like when Billy was in war, Billy does not want to live when he is faced with the possibility of death. Of the few things Billy voices his concern about, he talks of letting himself die. I think that the emphasis Vonnegut makes through the irony and repetition is that Billy will die when he is meant to die, and the course of the world cannot be changed.