This is pretty great. Don't read it if you hate stereotypical romcom tropes because that's exactly what this is. Misunderstandings galore.
You have the stereotypical Idol character falling in love with the plain boy MC, a "rival" heroine (who functions quite differently compared to the childhood friend archetype), and for once, a male friend character who isn't completely sidelined.
The "rival" character is written to be the perfect partner for the Main character, but because they're so alike, their differences make them hard rivals, and as such, are unable to even consider romance. Nevertheless, I'm hoping the two get together in the end. Probably not happening though. "First heroine" trope says first girl wins.