What makes us ourselves

We interpret things differently. This has become very clear to me the last months. First off, you need to know that I live in constant pain. Constant, as in all the time. 24/7. So when I say "I'm alright" I mean "no worse than usual" - which includes being in pain, feeling nauseous, muscle weakness and difficulty focusing. When I say "not doing so good" it's a worse, want-to-stab-myself-in-the-neck or can-I-die-soon pain.

People around me don't understand that. They see "alright" or "can't sleep" and they make comparisons to their own aches. And I want to slap them. Do they know how lucky they are? For one or a few days they're in pain and then they're not.

I turn bitter. I wonder what right they have to complain. And I react in a way seemingly violent, seemingly illogical and irrational.

And that's why your characters don't need to make sense - not to everyone else. As long as you know the reason behind their reactions, fine. Their personal problems and hang-ups make them themselves. It gives them personality and a life outside the pages. You might need to have them snap somewhere in the story or make a friend of theirs explain the situation to the main character. Or you can show these issues to the reader through internal 3rd person POV.

Or maybe you don't mention it at all. The world is full of people we will never understand. It only makes sense if your main character encounters a few of those too.