Cannes: An unabashedly melodramatic and sexy film offers an unflinching anatomy of a couple

That dress No, Natalie Portman did not rob The Metropolitan Museum of Art. There were spontaneous combustions among fashionistas when Natalie Portman, attending the premiere of Todd Haynes's future camp classic May December, arrived in a Juno dress on the red carpet. Designer Christian Dior's intricate 1949 frock - a landmark achievement in skirt construction - is currently housed at the Metropolitan Museum of Art. And with good reason: (a) it's priceless, and (b) the petals are made of gelatin and would instantly dissolve if surrounded by the heaving paparazzi at Cannes. Portman's gown was a replica of the 74-year-old…