What do narcissistic people really want in a relationship?

I posted a few weeks ago on this sub trying to understand if my husband could be a narcissist. It doesn't matter anymore whether he is or not, he is affecting my well-being.

I have observed him and he is miserable too. All responsibilities are a burden on his dainty little mind. But he is quite angry at me since I mentioned leaving him. He is passive - aggressive and I have started to observe him more closely. His style is to break my confidence slowly and subtly. Like instill doubt, make second-guess my decisions, silent treatment, mean jokes, etc.

So I am trying to understand why is he in this? And what I can do to cut off that supply? What am I giving HIM that is making him stay? Has anyone figured this out?