Part 3 still has some updates to go. The parts are all about fitting into a small APK for android devices.
As far as picking girls, I wouldn't expect it. Part of the reason the story in this game is so good is because all the girls interact with each other, and all are mandatory. Building out combinations (in this game or a future one) would add a massive amount of story branching and development work. This would likely lead to their stories all being less intertwined like many other games with a configurable group of people.
I totally agree with you, man. I think the reason the story has turned out so smoothly is that they didn’t need to create branching paths that are hard to manage. They just focused on telling a single storyline and made it this good. I think if someone could handle multiple storylines perfectly, in terms of branching paths it would be way too complicated and exhausting in my opinion (if they could do it and make it great, they’d be God-tier writing for sure). So yeah, I agree with you. But about wanting more choices—if it’s possible in the future, I’d want that too, definitely.