Die Marquise von Sade (1976)

Lady Doriana Grey, who haunts her isolated castle, and her twin sister who has been driven insane after being institutionalised at a young age. In the mental facility, the sister is under the care of Dr. Orloff. The two share a psychic connection, and along with their similar looks, they apparently have another common bond. It would seem that Doriana is unable to experience sexual satisfaction. Her enigmatic presence brings her many lovers; mostly female who are unable to resist her charms. In succumbing to their lust for Doriana, they pay the ultimate price. As she brings them to orgasm, they perish as a result. This curse is apparently what keeps her young and enchanting. The lunatic sister on the other hand experiences everything, including the orgasms her other half is unable to achieve. She revels in the feelings her sister's lovers project when they are in their final throes of life and passion.