The acting and direction and writing of the love story has nothing to do with depictions of mental health conditions and everything to do with George’s actual arrested emotional and artistic development.
He thinks like an 11 year old (and sometimes this is his strength) Only really gifted actors and directors can get those thoughts to feel like something real people might do.
My wife and I have long suspected George has Asperger’s. This is not an insult (those who know me understand why) but an observation on both his strengths and weaknesses.