You, try to understand them.
Then, do all that you can.
And say no to all that you can’t.
Without feeling guilty about it.
Here’s the most important part though:
Bless them whenever you think of them. Often the problem lasts a minute, the extrapolation of problem in your presumptuous world continues. Which harms the relationship more.
It takes one person to change any relationship, including a work relationship. Bless the other person without killing yourself, and you will never not find a way.