he has other things on his plate.
That's not really a good explanation, considering he dismisses everyone around him.
Sharon: "Hey, how about we..."
PC: "Sure sure *pat pat*. Now back to your paperwork. I'm busy actually progressing the story and you're not really a part of that anymore, because you already joined the harem. Sucks to suck on my flaccid vamp dick."
Laurie: "... =("
PC: "You're fine!" *clinteastwoodface*
The old adage of you are what you eat comes to mind here. You just drained not one but two depending on your decisions very nasty people. Incorporating thier personality traits so to speak.... Sharon did warn you from the beginning about how the blood changes you and that you should limit your access to it, and the longer you can hold onto your humanity.
Would be pretty nice, if this was actually established in the story somewhere. We already have the foreshadowing from Sharon, as you mentioned, but things don't really line up and Sharon's lessons are all but forgotten it seems like. The first two episodes really had a very different vibe and the shift is pretty obvious, when playing from the beginning again.
To me it seems like the PC was always supposed to be a daddy dom power fantasy. The problem is that, if you're not into that, you're probably frustrated by the lack of (or sudden jump in) character progression and how every other major character got sidelined heavily. But if you're into the daddy dom harem thing, then every explanation for it is probably good enough, because you're enjoying yourself anyway.
For example, the PC started talking in short pointed sentences and implied headpats, because his low generation vampire powers made his jaw grow into Chad proportions, so it's difficult for him to talk without letting his chin hit the floor. Trust me, it's in the lore.