I prefer Kaufman to Heinley too, but sadly she thinks that everything is the result of the love potion because he is just as good (normally) at ignoring his own emotions as she is. It would be hard for them to have a healthy relationship until one of them is completely self-aware AND honest.
Meanwhile, Heinley fills the role of Manic Pixie Dream Boy. Not my preference but he works in the story.
Rashta makes some really selfish and in some cases evil decisions. Mostly she is ignorant, not completely stupid, and the only person who is honestly trying to help her is the Baron who is teaching her to read. Even Sovieshu only sees her as entertainment or an ego boost and now the Mother Of His First Child. Duke Ergy seems to have his own agenda.
So I don't hate Rashta nearly as much as I hate Sovieshu. He is clearly selfish, thinks the world revolves around him, and is bad at self-reflection, so he hurts both Navi and Rashta indiscriminately and then blames them for it!