Ah, DF, I really appreciate that you've almost completely memorized this damn script, and yes, everything you said perfectly summarizes this story... the rest (from Act 3 onwards) is for drama and because the author adores Lacey, they have to make readers believe she won't evolve, or at least won't try (as the professor says, Lacey is Lacey).
Besides, the end of Act 3, where MC leaves, is designed so that in the following act Lacey finally gets a real wake-up call, thinking she's truly lost him... at least I hope things will get a little better from then on... I say a little, mind you, Lacey has to stay Lacey.
And for those who keep visualizing the possible endings, here's a message posted by the professor himself that explains everything, plus the two essential characters, "Anna and Mia," who will be part of the story until the very end:
1)Professor Amethyst Games:
So, I thought I would address this important topic. There is some forced interaction with a secondary LI character in this act, but you control how far it goes. There will also be an extremely significant forced act with another secondary LI in act 4, but it's a big part of the story arc, so there's no way to specifically avoid it. However, after that big moment (which is alluded to in act 3) there will be no additional forced romance interactions and you will have full control after that with who you choose to keep and who you don't. There are seven possible endings to the game. One of the primary good endings (there are two of them) it is just Lacey and the MC. As for why there is some forced interactions this far into the game is because these two LIs are major players in how the game unfolds. A word of warning. Each secondary LI has three possible endings (happy, neutral and broken). If you care about a LI (even if you don't romance them), aim for their neutral ending.
2)Professor Amethyst Games:
I really needed to come back and dig into an important story concept here. The MC absolutely loves Anna and Mia. So, you can still choose to only end up with Lacey. But that won't change that Anna and Mia are found family for the MC and Lacey. I bring that up to explain why the MC has such strong feelings toward them.
In short, for the different endings, it will be up to you, the reader, to decide what you want these two characters to become... As for the secondary characters, that will also be up to you. Look at what the Professor says: (If a character is dear to you, even if you don't have a romantic relationship with them, aim for their neutral ending.)
All that's left is to prepare your save files (I trust you, DF:LOL

and wait for the sequel.