One thing about "high maintenance" people is that you are not obliged to provide their maintenance. You can choose to, but you can also tell them "You're being high maintenance and I can't keep up. These are the things I'm able and willing to do for you: ---, ---, ---. If you have more needs, you'll have to find other ways of having them met."
When my girlfriend and I started dating, it quickly became apparent that she's high maintenance, and that I wasn't interested in taking care of all those things. Fortunately, she recognizes that she's high maintenance. We had a really good talk about it, where we established what I am and am not capable of providing. She decided that she liked me enough that she was willing to take what I could offer, rather than walking away entirely. It's been great ever since.
Of course, that does require the high maintenance person to have a certain degree of self-awareness and personal responsibility. Lots of people who are high maintenance to begin with also happen to think it's everyone else's responsibility to make sure they're taken care of. But those are exactly the kinds of people I refuse to even consider dating...
“As I am sure any cat owner will be able to tell you,
someone else putting you in a box is entirely different
from getting into a box yourself.” —bisexualbaker