Look, some people are just negative. They are hard-wired to see the fault and see if and how it affects them first. That will always be their first reaction and their default setting.
It doesn't mean they aren't kind people, or even good-hearted or fun-loving, but... BUT, that trait will always show up. They will always find the one note missed in a beautiful song of thousands of notes. They will always find a way to be stressed or unhappy, even in the best of circumstances that so many others would consider a dream. If they have food, it's the wrong kind... if they have water, it's not what they wanted, if they have a roof, it could be better. If they are dieting, it's the worst ever. If they have lost weight, it's not enough. They will always want more and more and more... whatever it is, it could be better or different. They are just never going to be satisfied.
So, stop trying.
Life your life. Do what you are going to do. Go where you are going to go. Let them come, or not. Let them join, or not. They will be confused and hurt when you retreat or don't always seek to include them. And rightly so, either love them or don't love them. But don't be their "sometimes" friend. But, under no circumstances are you required to cater to them or ensure their happiness is secured ahead of your own.
The world is a big, beautiful, fun place - and even with the horrors that hit us daily - it's still great to be alive and sentient and able to pursue your passions and life paths. Do not let someone else hinder and derail that. Invite them along, but don't stop for them.