It's easy to say 'just talk it out' or communicate but most of the time it's one of the hardest things to do. It would be the best thing for them right now but i don't think Nan has it in him (yet), nor was he used to talking things out when having trouble because of how he was brought up. He has to learn though.
I don't know what it is but the author did good writing the characters. The complexity of their emotions make them more human.