Why does Rowdy tell Arnold, “You killed her” (211)? Is there truth to this statement? (Alexi)

Rowdy tells Arnold that he killed his sister because there are reasons as to why Mary left that were because of Arnold's actions. Rowdy was starting to blame Arnold when they ran into each other in the woods, "...She was only living in Montana in a cheap trailer house because I had gone to school in Reardan. She had burned to death because I had decided that I wanted to spend my life with white people," (Alexie 211). Arnold is blaming himself for the death of his sister because of the actions he had no control of. Although what he did led up to his sisters decision about moving away, he could not have predicted that. He did not make the decision to go to Montana or go to the party and get drunk his sister did. His choices may have influenced hers but in the moment Arnold was not thinking that way and was not expected to. Arnold would obviously not do this on purpose and if he had realized what he did before he would have stopped, he loved his sister too much, she was different just like him.