Don't you only get that by asking Mia to help with Elsa, if you just ignore Elsa you can do all of Mias content without her
You can't really do all the Mia content, because her content goes tied up with the Elsa content, in fact if you don't do the Elsa content, you can't do the new content with Mia and the mother in this new update, since Mia is getting punished because the mother finds out that Mia had sex in class with another girl (Elsa). So while yes you can just start the game and then do all the Mia solo content but then if you don't do the quests of Elsa you won't be able to see the new content.
But that wasn't my point, my point was that Mia had oral sex/sex with Elsa without the MC knowing it until after it happened, then we were "forced" to be happy about that and even help her to fuck Elsa but now in the MC's bedroom and only after that we can join in a threesome. But in this update Mia finds the MC and the mother fucking and then gets mad and wants to be away from the MC for doing exactly the same thing she did with Elsa, fucking someone without the other knowing it, but while we were "forced" to be ok with it and act like it didn't matter and like she didn't cheat on the MC with a girl after declaring her love for him, she got mad, so I will call that bad writing.
Besides in on of the post of the author of the game, it was stated that we will have two routes to deal with the Mom-MC-Mia thing, either work with Mom or with Mia, but it seems like he didn't implemented it in the end so it seems like he doesn't like choices too much, a pity because I really liked the decision we could made preventing Julia to try her luck with the Mom, choices like that for the people that don't like sharing, even with other girls, would make any game great. If one of your lovers in a harem game sleeps with another girl without the Mc being pressent it's still called cheating, even if it was a girl doing it.
Sorry for the long reply
I went a little off-topic at half of it.