14Natalie Portman and Hayden Christensen - Star Wars Episode II: Attack of the Clones (2002)
While Attack of the Clones is not nearly as steamy overall as many of the other movies on this list, Hayden Christensen's Anakin Skywalker is supposed to be so over the moon with desire for Princess Amidala that he will risk the disapproval of everyone
important in both their lives. The scene that sees them flirting together in the fields of Naboo should be sexy, but they're more like a couple of toddlers rolling around in the grass.
Later, Amidala wears a flowing gown that bares her back and shoulder while they talk on a balcony (about sand...for some reason). Anakin's tentative caress of her bare skin should be tantalizing, but the look Amidala gives him looks more like annoyance. The kiss that follows is awkward, and their chemistry doesn't get any better for the rest of their on-screen relationship.