For me, it's different ones, such as "Careful, be careful" and "This is where the world drops off." These say a lot about Brian and Justin's new/old relationship. Careful can mean a lot of things, such as tread carefully, don't make the same mistakes. "This is where the world drops off" is a metaphor for Brian and Justin's way of shutting out evereything around them. When they're alone, they almost exist in a bubble. There's no one but them. I love that interpretation of the lyrics. It's so true for Brian and Justin.