I wish they were more explicit in what Sayoko is planning or the current state of her relationship/marriage, but I guess that's the hook they want readers to keep latching onto
it would undo a lot of the tension that currently carries the series, I think.
The moment we find out Sayoko's intentions, it becomes less of a guessing game about how much potential danger/misery Meari is in/in for, and a becomes more of a question of "how do these two resolve the obstacles in their way to achieve their ends?"
That feels more like an Act II sort of question, where we're still effectively in Act I (though the latter half I would argue), wherein Meari has internalized that she's growing more and more attached and dependent on Sayoko, beyond her former capacity of compensated dating. This isn't about money anymore for Meari; it's about the need she has for Sayoko, and the nascent feelings she's developing and realizing.
Sayoko remaining an enigma who is giving conflicting signals to Meari keeps the uncertainty surrounding their dynamic intact. The moment we get Sayoko's actual internal narrative, and her goals/intentions are made clear, the narrative will have to move forward into further establishing the conflicts surrounding Sayoko and her reasons pertaining to Meari, and it would progress their dynamic as they push and pull against one another.
That all said - I think we're nearly there, and we may even be entering it starting with this next chapter, which I think will have a dinner/party with Sayoko's in-laws given the beginning and ending. (And the chapter title as well, though I thought it also could refer to Meari seeing her "papas"(dad), and now Sayoko as her "mama"(mom). I'm leaning more toward it referring to the imminent future chapter for Sayoko, though.)
So "Act II" will be getting the other lead's side of the story, in effect. With Meari's desired goal of "needing & getting Sayoko" becoming established, we move to Sayoko's POV, flesh out her side of things, and establish her reasoning for targeting Meari and why she's continuing to hold Meari at arm's length.
And then the rest of Act II would be their conflicts playing out, as the tension mounts and things trend downard for them both and they see problems arise and exacerbate.
I could be wrong, or at least off in my timing of when we'll shift perspectives and start gaining insight, but that's at least how I sorta see the narrative trending, from a storywriting perspective anyway.