From the album Girlfriend
This is about choosing yourself after spending too long measuring your worth by someone else's attention. The garden is not a metaphor for the relationship. It is where she goes when the relationship is finally gone.
Out in the garden, I'm lucky again / Run with a robin and curl with the river bend
She is lucky to be alone. The rhythm of 'run' and 'curl' makes solitude sound physical and active, not empty. She is doing something, not waiting for something to happen.
You call, I say, 'No, no, I know my worth' / You're reaching out, no, no, I'm not your girl
The repetition of 'no, no' reads like she is saying it twice because once was not enough before. Knowing your worth is not the same as enforcing it, and this is the enforcement.
Lucky to be free from the hell of my pride / Lucky to be lonely and hold myself tight
Pride here is not arrogance. It is the part of her that kept going back. Being lonely is framed as the win, which only makes sense if the alternative was worse.
Got a message in that big blue sky / I'm no stranger to that sage advice / If you love her, let her find her life
She is talking to him but also to herself. The 'sage advice' is the cliché she finally believes. Switching to third person ('if you love her') creates distance, like she is stepping outside her own story to see it clearly.
Get the feeling that it's over now
Not 'it's over' but 'I get the feeling.' She is letting herself believe it gradually. The repetition sounds like convincing herself, not celebrating.
The best line might be 'all the roses are over, the fountains are dry.' It sounds like the end of a fairy tale, which is exactly what this relationship was. She is not mourning the garden. She is describing what is left after you stop pretending.