ok so i mean cooper knows he's mentally unwell somehow he does and he doesn't behave recklessly about it or pretend like everything is okay but he's been in the position before of doctors telling him he's ill and can't do things and he won't let that happen again. he just doesn't know the word for dissociation and pointedly will not use the phrase 'ptsd' out loud to describe his nightmares or any of the after-effects of his crash,, probably ever
he feels pretty negatively about doctors he'd rather fix his own problems and doctors can be saved for people who actually need them which, cooper will say to u, he does not
he also doesn't want his children to see him dissociate or know about that in particular because they already grew up with a dad who has chronic nightmares and when he was growing up he was never exposed to his parents' pain because his parents believed you don't expose your children to that kind of thing and cooper believes the same ('you want your children to feel safe')
he only learned about or realised his parents' struggles and pain at all when he was an adult himself and he knew a lot more. he couldn't stop murphy / tom finding out about his nightmares but he thinks he can try to stop them from seeing any of the way that he is or feels broken now.
((footnote reminder that i headcanon that both of coopers' parents were trans))