Oberon--follow Ashley's story through. I was a bit put off as well, but the pay off is worth it, as it lead to, to me, some of the most touching emotional scenes of the game.
Runey--May I just start off by pointing out I would absolutely never have thought I'd talk about "touching emotional scenes" in a sex-oriented game? Much kudos for that.
That said, I get Oberon's points, the character's extremeness can be difficult to come to grips with to begin with, and, more importantly, there doesn't seem to be much motivation for MC to allow her actions toward the other characters -- especially if you've advanced them more. For instance <spoiler>I advanced F&E to where they had their heartfelt moment with Ashley, but then advanced Ashley a bit more and so almost immediately after Ashley seems to be warming up to them, she then turns and runs the blackmail on Felicity.</spoiler> For me, it kind of broke immersion and I was like, "Why would MC just let this happen to these girls he's just enlightened some?" I wonder if this kind of thing might be alleviated by giving MC some dialogue options that at least indicate his disapproval of the infighting. Or alternatively, for some of the more extreme actions, such as the knife threatening, bring in a character like Ellen to take control of and have sympathy for, thus giving MC a reason not to simply toss her out for threatening other guests.
Basically, I wouldn't want a couple of rough patches put players off from following what is an otherwise amazing story arc.
Regardless, thanks for this, it's broadened my idea of what might be possible in an adult-themed game.