An entertaining “what if?” romantic comedy. Gwyneth Paltrow is Helen. We meet her as she’s fired, mugged, and betrayed by her louse boyfriend Gerry (John Lynch), discovered in bed with ex-girlfriend Lydia (Jeanne Tripplehorn). Or does she? What if she rewrote the script? What if timing, the Tube’s sliding doors, hadn’t marred that day? Writer-director Peter Howitt explores option no. 2 and makes merry with success and happy endings (Helen dyes her hair blonde and starts her own PR venture). In both scenarios, the key figure is James (John Hannah), friend and would-be lover. Howlitt depends wholly on Paltrow and Hannah, both engaging. To his credit, he manages the script deftly enough that it’s never entirely clear which reality is the real one, or more to the point, which one’s for optimists and which for cynics. No foul either way, and fun along the journey.