Considering all the changes from MNM I am pretty sure 'forgot to correct that line' isn't the issue, its more along the line of K7 deciding to change the background of MNM to fit whatever he wanted to do with this game, their are so many deviations that it can't be merely a question of mistakes, its intended. Which is why like I said before a rewrite of MNM is a necessity, otherwise the two games won't make sense one with the other.
I think you're right. At a certain point, too many soap opera plot devices are necessary to bring the two narratives in line, making it jarring and immersion breaking.
Having now played chapter 2, I can see how Bethany's attitude changes. At the start, like with the Katharina deal, she was very laissez-faire. But now
with the cousin-scare, reality hit her in the face. She seemed to have a very libertine view on sex and intimacy, even being playful about the MC discussing condom use with his girlfriend
s without batting an eye. But I can see her becoming a bit more conservative because of this.
As for Sabrina, it will now depend on
Lea and the MC continuing their relationship and if Bethany makes peace with it. If they continue and it causes a huge rift, then I can see this impacting Sabrina a lot. Otherwise, if Bethany is fine with it, it would encourage Sabrina, making her think Beth will be fine with her and the MC too (eventually).
I think Dev will eventually change some plot of the main game in order to match the change in the prequel.
Yeah, or designate MNMTB as happening in an alternative timeline instead of being a straight prequel.
The main
issue, narratively, is that the household is already becoming a powder keg of incest while they'll still be at the university for years. This isn't all happening the last few weeks before graduation, before they all split off to do their own thing. Katharina is the main driver of this toward Bethany and the MC, and then there are the MC's own feelings as well.
With MNM in mind, I had expected this story to have Anna as the main driving force, that she'd be the one pushing everyone together and convincing them their feelings aren't wrong. Then we'd have a conservative family and MC, with libertine Anna pushing boundaries.
Edit: In a way, rejecting everyone until Anna is there feels more canon to me.