I don't think there is a moral because we don't know how the lady and tiger ends. We don't know exactly what the princess will do. Will she give into her dark side and say "If I can't have him no one can."? Or will she be gentle and self sacrificing and let him live, even if it is with another woman.
The princess is so balanced between love and hate, that we have no idea what she will do.
The character that proposes the story telling competition that frames the remainder of the Canterbury tales is : Bailey After creating the competition, Bailey quickly appoint himself as the judge for that competition