I've been just lurking twop, then here. I'm enjoying your posts almost more than the actual shows.
After the last couple of episodes I've begun to wonder if Sonja is playing up to Aviva because she has decided to go all out after Harry (after all, the family has money, I understand) and feels that having Aviva's approval will seal the deal. Could it be that she has realized her future is not looking too bright. She really couldn't be as delusional as she appears. It could be an act. His family, I think, is old money--and it would give her some stability (maybe, and some prestige) more than her present situation. With the judgment looming and her general financial situation, it may be that she sees this as keeping up appearances with the social set.
Aviva and Harry have a comfortable relationship and her approval might mean a lot for Sonja.
After seeing first look I'm now almost convinced.