I agree with you HoneyB33
If there wear an anti-relationship like antimatter these people would be it. They are the most complete opposite of healthy. You summed it up perfectly. We would have to die to make them satisfied so what's the point.
Nothing will make them truly happy. They feel empty and broken to their core.
They will claim that X will make them happy. So you do X for them. Then Y becomes a new problem, and according to them it's always been a problem even though you've never heard them complain about it before. Then the cycle continues. It's so frustrating to deal with, you literally cannot win.