It's not that easy. A lot of decisions do work that way, yes: You pick an option and you get an affection point if you made the right choice. But there's also a bunch of choices that are more nouanced: Maybe you'll get the affection point later or maybe the game won't even show you the affection point gain. Maybe multiple choices yield affection points, but one yields more than the other.
Also, some people prefer to play the game in one go without having to rewind back and forth to experiment with different choices. That's what walkthrough mods are for. And for him it's already too late, he already lost a path. So I pointed him to a document that helps him understand what went wrong.