Do you think there's time for any of the side girls to become MG for the final few episodes? I abandoned the Quinn route because I just never liked it. So to me, that really only leaves Rio and Lily. Lily seemed like she was really open to being more than just rollin and Rio obviously had serious ambitions toward MC. Am I missing anyone else that seems like more could be made out of it? I don't count Zoey in this because to me, Zoey is MG material.
I also think I have to playthrough a few more times to revisit some of my earlier paths like others w/ Jade route. I forget how the whole fallout over the Burke divorce plays out with Jade and MC.
Rio, Lily, Quinn, Nicole and Nora are the strongest SGs and I could see them catching up to where the MGs are now, if there are say three more episodes + epilogues. But by then the MGs have gotten further ahead. The only one who can compete is Zoey. She isn't building a relationship from scratch like all the others, but revitalising a past relationship.
At ep 8 the five MGs had their own paths. They had progressed so far that MC thought he had to upgrade the relationship to a serious level or stop leading them on. Everyone else got lumped to the Others path as girls who had not at the time progressed far enough to be taken seriously. They have been catching up to that during S3, but the five MGs are all getting further and further ahead as well.
But the ep 8 choice does not define what Zoey is. The choice predates her return. Even if she isn't exactly one of the MG she is at least an entity on the same level and ep 11 confirmed this with the option to switch to Zoey.
The SGs have great potential and in the long run their stories might end up better than the MGs, but they won't catch up to them by the end of this game. But the end of the game doesn't have to be the end of the characters. It won't be canon but it wouldn't be the first time a fan produced better writing than the original creator. Or better art.