Hello.
My English is not good, I use machine translation below, I hope it doesn't bother you.
It seems that the act 2 finale can be entered without having a relationship with many girls (it seems that only Asteria and lyx are necessary)
If you skip the relationship with many girls will have an impact on the subsequent plot?
Also about act 2 finale, I remember in the murder story (or maybe not the murder, I don't remember it very well), Morgana said "this realm has nothing that can break my defenses".
Then gwen knocked her down with one punch, LOL.