(featuring Juliet Simms)
But it could also referred to as if the girl has already killed herself.
In the end, the boy realises and she's gone for good and won't come back, so he needs to learn to move on. He seems to be trying to convince himself that it's best if he goes home, since it repeats the lyrics several times.
I think the moral lesson that you can get from the song and the real meaning is that don't take too long to convince your feelings, before it's too late. Because regrets always come in the end.
By the way, you can listen the song here: Remembering Sunday - All Time Low
meaning of the song: http://www.songfacts.com/detail.php?id=13313
details of the band: https://en.wikipedia.org/wiki/All_Time_Low