I agree that the last part of the song is more like a monologue and not a message for the lover.
When he says "Oh sweet Christabel share with me your poem", he's not asking Christabel to share her poem. I think it's a stylistic form that means "Oh sweet Christabel, I'm sharing the same fate as you and your unfinished poem." Coleridge planned to write more but never finished it.
He feels unworthy of calling himself a poet because according to him, he never managed to find a conclusion to any of his poems.
I agree that the last part of the song is more like a monologue and not a message for the lover. When he says "Oh sweet Christabel share with me your poem", he's not asking Christabel to share her poem. I think it's a stylistic form that means "Oh sweet Christabel, I'm sharing the same fate as you and your unfinished poem." Coleridge planned to write more but never finished it. He feels unworthy of calling himself a poet because according to him, he never managed to find a conclusion to any of his poems.