In Robert Greene's novel Gwydonius; The Carde of Fancie, the character Melytta has guessed that Castania has fallen in love. At the end of a long speech, she says to Castania (italics from the original),
But if in all these supposes I have mist the marke, and have not toucht the case of thy calamitie, unfolde unto me Castania, what the paine is that thus doth pinch thee, and assure thy selfe I will be so secret in they affaires, as ever Lampana was to her Ladie Cleophila.
What story is Melytta (or Robert Greene) referring to? I have tried several searches varying the spelling of both names but came out empty-handed. Or did Lampana guard Cleophila's secret so well that no one could write a story about it?