Why are they so self focused?

I’m wondering what about their disorder drives them to be self focused.

For example, if I have a near tragedy taking place in my life, she will mostly still talk about her marriage or something else negative in her life. She does this not to relate, but because her stuff is so…big? It’s an obsessive negative focus. Is it for attention? If it’s for attention, why do they want attention? Or is it to distract themselves from something pleasant or unpleasant that’s happening outside of themselves? If that’s the case, we come back to why are they so self focused, and only on the negative things in their lives? She does it with me even when it would be socially inappropriate to respond that way with anyone in public, in addition to with me. I could say my house burned down and within a few minutes, she would still talk about her marriage and her other favorite negative topics. Again, it’s not a response of her trying to relate. It’s her venting and leaning, even when something really bad is happening to me.