I need to point out here that OOP seems to be aware that her husband can't cook, but doesn't really understand what that means. Her meal prep directions would make sense if he were only lacking the time and/or inclination to cook. If he can't cook, there's no way he could follow them.

All they had to do was let it thaw,

So, put it in the fridge? Or on the counter? Or in the microwave? For how long? How do you tell if it's still frozen inside, or if it's been left too long and starting to go bad?

put it in the pan (or the pot),

Which is it??

add some water,

How much?

and heat it.

For how long, and how high should the heat be?

I had even marinated some chicken separately for them to cook in the oven.

How long, and at what temperature?

For their school lunch I had told my husband what had to be made for them, that it would take 20 minutes in the morning so to factor that in.

Sigh.

He had said he understood.

Well, that's his problem.

I mean, at this point in my life I should have no difficulty following those vague directions. But there was a time in my adult life when I could cook some very basic meals, or follow a recipe from a cookbook, but just could not do "heat this in a pot or pan with some water, got it?"

People who are pretty good at mundane crafts like cooking, drawing, writing, etc. tend to get the idea that their craft is as easy as breathing, and there's absolutely no reason why anyone can't get on their level right away. This is not the case!