You have to tell him to do what he wants to do instead of what he thinks is right when you have the choice to comment on whether he should go back to his old job or not. I think you have to have max heart on him as well, but that choice is the main difference between good or bad end, I'm pretty sure each guy as a similar make it or break it choice in their routes as well. If your not sure which choice is better, it's always good to keep a save that puts you back at the choice screen, but you can usually tell by his response to your choice if it was the right option.