In synopsis, this strongly reminds me of King of Hearts (1966) which I’m sorry to say I’ve only seen bits of, but which has a very similar premise, particularly a literally unearthly, beautiful, hothouse-fragile romance that tragically cannot survive its make-believe setting.

(In cinema - and in television also - 1966 was an astounding year, a Harmonic Convergence of quality not seen since 1939.)