I'll do my utmost! And no worries, Nicki will be back in Chapter Four, for a couple of fun scenes at the beginning of the chapter.
That's a fair concern! I definitely tried to be cognizant of that when I started developing the game. I've played a few adult VNs that I've seen derailed by ballooning casts.
I will say this - the plan was always to have certain characters take center stage for a while, before ultimately stepping back a bit so another girl can take a more prominent role. I think of those first three chapters as kind of being Nicki's story, examining her relationship with the MC, taking it away and showing who he is when she's not there, and finally reuniting them to see what their new dynamic looks like. But, now Nicki's story is basically resolved for the moment, and her next few appearances are more like character moments and fun little sex scenes, without all the drama.
So, with Nicki's main story taking a backseat, I get to devote more focus to the Barron family. Next chapter will see serious advancement in Gabby and MC's relationship, no matter what path you're on with her. And we'll finally see MC and Madison interacting in a more significant way.
At the same time, we'll see the return of Nicki, Ashe, Brittani, Mason, and Carolina. For some it'll just be a quick appearance, for others, more of a full scene.