There is an entire DSM-5-TR cataloguing the many facets of 'mental illness'. His psychologist diagnosed him with PTSD and a major depressive disorder after the accident, and he also shows signs of apathy, impulsivity and manipulation, and self-injury when he feels overwhelmed. That doesn't make him a sociopath (anti-social personality disorder), but it does mean that he is clearly still in need of psychotherapy. (I would actually clock him closer to borderline personality disorder)

This is one of the reasons why I agree with the time jumps of years. He's not going to get better in two months. Love is not going to fix him. You can't just tell someone with depression to 'just try and be happy'. Nobody would be depressed if they could just turn it off. Same as, nobody wants to have PTSD, panic attacks, and triggers. He's doing better in 4 years than how he was at the end of high school, but every day is a new day that he has to work through.