Christina -
 
  Wendy Flory's piece "Tre Donne" in PAI 5/1 (1976) was, I think I remember,
such a piece. It went into her book "The Cantos: A Record of Struggle" (Yale
1980), into the chapters on the later Cantares (if my memory is right).
  & maybe you'll find something in Omar Pound/Robert Spoo (ed.), "Ezra Pound and
Margaret Cravens - A Tragic Friendship 1910-1912" (Duke 1988).
  EP's daughter Mary's "Discretions" may help you ontothat track, too.
 
  All in all - a delicate topic. As you might guess from biographical evidence in
the 1st place...
 
  Best,
 
  alex