I think the song is about one person (Aly or AJ) ending the relationship but they're still not completely over them but then they see the person they broke up with "hanging out with someone new" and that shows them that they're ready to move on and then HOW they move on and they're getting closer to closure.
I think the song is about one person (Aly or AJ) ending the relationship but they're still not completely over them but then they see the person they broke up with "hanging out with someone new" and that shows them that they're ready to move on and then HOW they move on and they're getting closer to closure.