When this dull adaptation of Natalie Babbitt’s children’s novel, about adolescent love and a fountain of youth, isn’t boring you to tears, it’s causing you to raise an eyebrow. As the two young lovers (Alexis Bledel and Jonathan Jackson, both of whom have the shiny, scrubbed faces of cherubs) frolic in waterfalls and dance under the moonlight, cynical minds may be reminded of the creepy underage indiscretions of Blue Lagoon.