The devs put "spending time with best friend" as an option so that you can skip time faster to focus on your main girl target. Unfortunately for the developers, his target is not a girl.
Misaki might be unobtainable but that only applies in the present in-universe.
Once MC clears the main game, there's always a chance that a hidden "Misaki route" opens up.
Or, well, I guess one of its fourth walls is missing. The characters are all fully aware that they're in a video game, but they're not aware that they're actually in a manga lol.