On re-watch I recall how Kathryn, when she is not being angry and defensive, seems to me so immature and socially uncertain, as well as uneducated and unsophisticated. Yet I also see why Shep used to talk about her being a sweet girl underneath. It was nice when she commented about the beautiful natural area around the tree houses and that she felt like she never took enough time to just look at the sky.
When she defended herself at the dinner table and said how hard she was working to organize herself and her life, I sympathized. She seems like a person who has had to learn what most of us consider basic life skills. Maybe it's because of how deeply into drugs she got, and/or maybe she has ADD that was not diagnosed until recently. I think in Thomas she saw a father/protector figure who would help her manage her life, and not having any time to actually get to know her, he expected way too much. The other gals seem to like her well enough now that they are more aware of how Thomas jerked her around and they've seen her fight to stay sober, etc.