Forget that she's an Idol. The fact that she don't have a father figure and our MC unknowingly giving her that much attention is what makes this manga seems like a borderline child grooming.
As much as I want to say for him to meddling to her father, because potentially of her abusive father, if it's me it's really hard to do so by myself. Oh well, it's just a manga. No need to self insert too much. But it's interesting how the story goes.