i think this song means that all these girls are falling for this guy and shes trying to tell him before he goes off with some other girl that none of them love him as much as she does.
or that the guy is going off somewhere or moving(i get that thought from the line pack up and when she says wait)and shes telling him before he moves that she loves him like no other..
this song reminds me of this guy that i like. i go to skool with him and i sit next to him. three girls(me and my two friends) like him and i like him the most, so this song kinda reminds me of that.

this song is so sad!! whenever i hear it i run to chack if my sister is still in her room!!! i started crying!! its very touching...