Britney Spears has successfully cast new beau Isaac Cohen under her spell. Despite the popstar telling a few paparazzi photogs that she and the model "weren't together anymore," the pair are definitely still an item. "She was joking," a source told Us mag. "She's the ultimate sweetheart," Cohen gushed to photographers recently. When asked if their relationship was the real deal, he added, "I'm taking it one day at a time!"