Small Town Sins question

I think every man regretfully encounters a LeeLee in his life. It's like she exists simply to torment. What's her problem? What motivates her? Is she just a female version of Nathan (greedy and selfish) without a Paula to complement her?

[Spoiler warning]
We don't know what comes of Nathan's cliff hanger ending. But suppose he's able to save Paula. And they burn the money. Wouldn't someone eventually pin LeeLee's disappearance on him?