he told me that he doesn't understand this "demon" that drives him to only see the negative
I find it hard to be positive about my S (you may have noticed...), but then I have to force myself to be positive in many areas that others would naturally click to. I can't say for sure for your H TTA, but for me, I'm so used to hearing how I did something amazing, but I missed a/b/c, that I've grown up seeing what was missing. I think if teachers knew I had ADHD, they'd back off. Because they didn't they expected equal or more...one good reason not to diagnose unless there are serious problems with quality of life.
I'd worry little about this...he can learn about this through his IC. The only thing to do is pray that he's got an excellent IC who is aware of DB, not divorce making.