Dylan is first and foremost their son. I don't see any romantic feelings that Sophia has for her son. It's still Dylan stalking his mother and crossing lines that are just embarrassing. (Exception is the photo event).
That a mother is proud of her son and also feels incredibly protected after Dylan knocks down one of the drunk men is normal and has nothing to do with romance. And looking someone deep in the eye is not necessarily an expression of romantic feelings either.
The difference from before is that Sophia feels comfortable with Dylan in a different way, because she increasingly notices that her son is changing, becoming more adult. He goes from being just a child to a son and a young adult that Sophia enjoys being with. But she still loves him only as her son. There is no trace of romance.
Where they see perhaps changed feelings, I see only a corrupted woman who finds it increasingly difficult to deal with their horniness. It is not the rise of Dylan, but the descent of Sophia that makes sexual interaction between the two possible. Not romance, but moral degeneration.
Dylan doesn't have to get better at all for sex, his mother accommodates him.
The switch
Dr.Fapalot talks about is therefore not necessary at all. Sophia does not need to see Dylan differently at all.
But, and here is the stumbling block in my argument, this argument of Sophia's moral degeneration to this point only works in the context of all the events Sophia has participated in so far. If only the Dylan route is considered on its own, Sophia's corruption is not enough and we get the break/inconsistency in the Dylan/Sophia story that many complain about.