I knew this song was about Paul's herion addiction. This scene is something out of Wizard of Oz, when they were in the field of pink flowers and fell asleep, which was itself a metaphor for heroin (and the "snow" was cocaine, hence why they wake up). Plus listen to the lyrics "Her canvas doesn't leave a mark that I can see" basically talking about track marks you usually see with herion addicts but somehow Paul was able to hid it from them. "Maybe I should let her go/But only when she loves me/How can I just let her go?/Not until she loves me" is a reference to the actual addiction. The "love" I think is the high from the drug. The "girl" in the song is heroin.