I think this song is about a guy, whose best/good friend is a girl that he has a crush on. But she's hung up on another guy, who's like super cool (thus, "rockstar"); and the guy is trying to tell his friend not to waste her time because the "rockstar" is over/not into her. But she just won't realize that, so she keeps on trying to win the "rockstar's" affections, much to the guys dismay and frustration.
I think this song is about a guy, whose best/good friend is a girl that he has a crush on. But she's hung up on another guy, who's like super cool (thus, "rockstar"); and the guy is trying to tell his friend not to waste her time because the "rockstar" is over/not into her. But she just won't realize that, so she keeps on trying to win the "rockstar's" affections, much to the guys dismay and frustration.