It's hard to understand why people put up with narcissistic abuse. Because of that, many assume that the victim is "codependent," which usually translates to "a glutton for punishment."
But isn't it pretty far out to so easily assume that people seek pain? We are hard-wired against that! So why jump that far in jumping to a conclusion? This isn't the same as the "martyr complex." People with the martyr complex aren't being abused. In their own estimation they're being underappreciated. Not the same thing at all.
Virtually everyone who has ever loved a narcissist gets angry at him- or her-self, asking why they put up with the abuse. They ask themselves, "Am I a glutton for punishment? Why don't I leave? Why do I keep getting suckered back into a relationship?"
I have this much comfort to offer: You are reacting to narcissistic abuse the way normal people always do. Not that you should keep it up, but there's no reason to get angry with yourself or to wonder what's wrong with you.
This isn't to say that you might not be psychologically injured. Counseling might well be in order. But that doesn't mean you're crazy. The narcissist is the one who's crazy.
You are in a situation analogous to being on another planet with an alien who views you as prey but conceals that from you. The inner person in you is as far from its regard as the inner soul of a cockroach is from yours when you stomp it. In other words, this alien doesn't relate to you humanly it is unaware of any common humanity shared by you both.
It relates to you as but an object. And that means exactly what it says: you might as well be a microscopic specimen or a nail this alien is hitting with a hammer.
Yet you are interacting as with another human being. That makes you dead meat. The norms of human interaction don't apply. Things don't mean the same to a narcissist as they mean to you. Narcissists are always acting on some alien premise that makes their reactions to things off-the-wall in our eyes. We aren't biologically, psychologically, or intellectually equipped to survive in such a world, which is rather like being on psychedelic trip.
We just make all kinds of wrong assumptions, that's all. So, it's crucial to make the effort to understand what's going on and to never, never, never, never go into denial.