I agree with lilb0idon, I think the song's about a relationship that's not reciprocated. The person she sings of is not ready for a relationship...it's just not meant to be, his heart's not ready to open, likely because it's still broken by someone else. Later in the song, it almost sounds like she says "If this love's not meant to be" rather than "smile's not meant to be", but it's hard to say for certain. Walking the empty streets is a way she can help herself get over the idea of this relationship that's not going to happen and a step towards her independence. Although she still questions herself, just as she begins to make sense of it, she goes back and wonders if she was wrong, something that's very natural to do when you think back on your interpretation of a situations, and I think in the end she's still ultimately convinced herself that it just wasn't meant to be.
I agree with lilb0idon, I think the song's about a relationship that's not reciprocated. The person she sings of is not ready for a relationship...it's just not meant to be, his heart's not ready to open, likely because it's still broken by someone else. Later in the song, it almost sounds like she says "If this love's not meant to be" rather than "smile's not meant to be", but it's hard to say for certain. Walking the empty streets is a way she can help herself get over the idea of this relationship that's not going to happen and a step towards her independence. Although she still questions herself, just as she begins to make sense of it, she goes back and wonders if she was wrong, something that's very natural to do when you think back on your interpretation of a situations, and I think in the end she's still ultimately convinced herself that it just wasn't meant to be.