If Y'Gythgba appears in another episode, I am throwing that episode straight in the garbage. Her fast and shallow romance with Raphael is a monument to everything that has gone horrifically wrong with this show's writing.
Maybe it wouldn't be so bad if they brought her back as a character with zero mutual affection with Raph. I mean, they've done that before—remember all the complicated romantic tension Raph and Slash used to have together and how abruptly all that vanished without a trace in season 3? If good writing can be so unceremoniously deleted, then it should be easy to delete bad writing. :)