"He" is Mitchell\'s then-recent ex James Taylor; "she" is Carly Simon, the fellow singer-songwriter he moved on to. Mitchell doesn\'t think Simon has any better chance of "fixing" Taylor\'s damage than she herself did. I assume the line "She wants me to tell her what the trouble might be" means Simon turned to her for advice.
"He" is Mitchell\'s then-recent ex James Taylor; "she" is Carly Simon, the fellow singer-songwriter he moved on to. Mitchell doesn\'t think Simon has any better chance of "fixing" Taylor\'s damage than she herself did. I assume the line "She wants me to tell her what the trouble might be" means Simon turned to her for advice.