And as for why I thought she could be a potential LI, Sage from Being a DIK was also on the whole were just gonna be fuck buddies nothing more and she too just came out of a relationship but now as the story goes on she's more open towards pursuing something more long term with the MC hence why I thought maybe just maybe there is a chance that we can get a proper Rosa path.
Completely different scenarios.
Sage is a college student that has barely dipped her toe in the dating pool and has no idea what she wants when you meet her.
Rosa is a mature woman that's just come out of a long term marriage and wants her freedom. She knows exactly what she wants and that's to have fun.
Thing with Rosa is she isn't even looking for a fuck buddy, she just wants sex. Just a couple of casual hook ups and then she'll move on.
I do hate to be "that girl" in this instance but it's been clear from day 1 who the love interests are and who the side girls are. That was never going to change.
Rosa never once acted or even hinted that there would ever be anything more.
I honestly do find it really strange that you ignored everything said in the game here and came to a conclusion based on something that happened in an entirely different game under entirely different circumstances.