That would be nice to easily solve the problems since our MC doesn't swing that way, but alas I doubt it. He did try to make himself better for Rui, a girl, so I'll guess he doesn't swing that way.
He is going to stupidly try and get her to change sides from our MC to himself, but honestly, with the way that Rui has been interacting with our MC we know that she sees something different in him. I would doubt she would be swayed away from him and even says this chapter that she can't think of a single thing that would make her hate him...meaning she sees him in a light that means she wants him to be there always and that she will always like who he is. Our other guy on the other hand....I mean she easily broke things off with him after 2 months of dating because she didn't see it as necessary or going anywhere. I can't imagine time and changing himself will even remotely change her mind about him.