While it was a mistake from the beginning to go full blown two routes with his "work ethic", you are a bit mistaken about which it should have been. The Dad-Daughter route was more popular, one reason the Dad might have his flaws (e.g. former workaholic, unusually prude, at least from a European perspective), but is a halfway normal guy with a functioning relationship at least with his daughter. The Son on the other hand, it became clearer during the game, has major mental problems well outside the family situation and is a ticking timebomb.This never should have been dual-route game. No one cares about dad-daughter route anyways. That was Kyle's first major mistake. Working on both routes at the same time is inevitable burnout.