Diamonds and Rust doesn't have to rhyme. It's a masterpiece.

I know one songwriter here who almost never rhymes anything in her songs, and they're very good, so rhyming is one way of going at song lyrics, but is certainly not obligatory.

I think it's wonderful that she sleeps in a tree house 20 feet above the ground! ;-D She's a grand character and a truly beautiful and courageous woman.