Right, thats why steeling yourself for the possibility of having to deal with unreasonableness is important. If you run into it, the first step to dealing with it is to get someone to explain what they expect clearly, in relevant detail, and non-hyperbolically. This short-circuits the possibility of mere misinterpretation. They might have just been expressing their emotions but not yet grappling with their desires in concrete terms—doing so might bring them back down to earth. Then you can resume jointly problem-solving.

If that doesn’t work...I’m actually not sure. But I just started reading the book Crucial Conversations and it claims to have a relevant answer.