Being 'in denial' is a common human reaction to a distressing situation. However with brain injury the 'denial' is often more than this, it can also be an actual cognitive impairment which prevents you from seeing the full extent of the problem. Technically it is referred to as 'anosognosia' or 'lack of self awareness'. It is considered common in brain injury.

I know I definitely suffered from this, and put myself in dangerous and irresponsible situations as a result. I also made myself look stupid, for example turning up to work and pretending everything was fine when actually I wasn't even well enough to have a coherent conversation with someone and had to be sent home more than once.

I seemed to respond well to people sitting me down and presenting me with facts eg 'look, if you're finding X difficult, don't you think you need more rest before attempting Y?'. It was kind of upsetting at times but I needed to be told.

Good luck in all your efforts, I got over it and so should he. It's great that you've come on here and found out more about what's going on.