I think deep down she's just scared to death of being alone, being financially vulnerable, and being unhappy for the rest of her life. Yes, I know that's mindreading, but she's also said this. Almost as if she expects to be lonely and unhappy.
She can't think further along than a few weeks or a month at most; when she kept talking about me staying until we paid off our debt, I asked her what we'd do then. She said she had no idea, we'd cross that bridge when we got to it.