I believe D'Avin's reasons for leaving home are obvious and entirely understandable, and Come the Rain eliminated any ambiguities. John and D'Avin's father was severely abusive, his mother a drug addict who failed to stop the abuse, and life at home was effectively hell.
If John had also left home, we would be commending them both as smart survivors. In fact, I find than John's anger at D'Avin is misplaced, and it should be directed solely at his terrible parents and his own choice not to leave. Blaming D'Avin is little more than insisting both them should have indeterminately suffered abuse.