It's more of an overarching thing, rather than "characters must behave the way they think they will."Although ultimately I think the only true reason is your last one since large portions of the narrative is characters doing things they don't want to or that they didn't think they were capable of.
Removing every scene that was "contrary to the foundation of [...] character(s)" would result in no Carnations since they're all betraying themselves in some regard.
I'm talking about how Edwin and Victoria's relationship informs other components of the story, where I want that to lead, and how it was pretty much the first thing I conceptualized writing even before the sex club aspect got folded into the scenario. What I'm trying to say is that, at it's core, this is not an incest story. And sure, it's all made up and the story can twist any direction one pleases, but it'd be working against the logic that has been built up and followed in my head.