1. Which... would mean everyone should remember? In the current state not even Tyson remembers, this is about as even as we're going to get.
2. Because he goes and doses himself with something that warps his immune system which now makes the medicine a mismatch. I could write that in to be more explicit but I worry that a lot of solutions that equate to "just have someone explain it somewhere" is going to make the wordiness problem worse.
I wonder how much of this problem exists because public demo doesn't have access to the epilogues yet. Though it's hard to gauge just how well received those are too. It feels like I'm being disrespectful to adopt a "If the message of the game didn't resonate with you, there's nothing I can do" mentality; and I'm hesitant to stick to that as my defense.
Shy of a ZTD style ending where everyone remembers everything and comes out of it with a complete character arc into questioning why their affections haven't been reciprocated mess, I don't think there's any better solution I could've taken. Epilogues cover Dave trying to expedite the character arc healing process but he's Dave, so it doesn't go well.