You can't be serious...

The song isn't about a girl..or a stomach ulcer.

The song is about inspiration & losing ambition: "My beautiful bird has gone away"
He is frustrated because he knows what he wants to be..but he doesnt seem to have the means inside himself. He wants to be the bird..he wants to feel that free with what he does in life..but he can't so he resents the bird.The bird is a metaphor..his drive in life..his antagonist to be something better than he is...& In the song he feels he can never reach his potential IE: "be the bird"...so in effect the bird becomes an object of hatred to him. The bird in this song is a constant reminder of how much of a disappointment he feels he is.

Peace