It's about cheating. He treated on the girl who he actually cared about. She was his friend, his confident. However, he then cheats on her, and she catches him. So she leaves.
"Should've known better than to cheat a friend
and waste this chance that I've been given" - So, he cheats
"We could have been so good together
We could have lived this dance forever
But now who's gonna dance with me?
Please stay!" - She leaves him for it, and the gulty feet is that he has guilt over doing it.
It's about cheating. He treated on the girl who he actually cared about. She was his friend, his confident. However, he then cheats on her, and she catches him. So she leaves. "Should've known better than to cheat a friend and waste this chance that I've been given" - So, he cheats "We could have been so good together We could have lived this dance forever But now who's gonna dance with me? Please stay!" - She leaves him for it, and the gulty feet is that he has guilt over doing it.