You probably already guessed it, but this scenario is heavily based on the song "Sk8er Boi" by Avril Lavigne.

{A} was known as a "Skater boy" by the entire school. They sang, wrote songs and played guitar. They loved {C} more than anything.
{C} was known to be quite popular in the school. They did ballet, and wanted to be with {A}. They wanted it so bad, but all their friends disliked them. Eventually, {C} was convinced to hate {A}. They turned against {A}, which destroyed them completely.

{B} met {A} three years after highschool,in a bar. They found {A}, broken, dream-shattered. They are the one that picked {A} up, brought them back to their feet. They are the one that helped them make some covers and songs on YouTube. Eventually, they helped {A} making their first album, which blew up immediately.

Now, {B} is going on tours,interviews with {A} and, to their surprise, at the first row of one of their show...Stood {C}, watching the skater boy who became a rockstar. They were not awaiting the last song to be talking about their story.
Not at all.