A source tells the new issue of Us Weekly that the Green Lantern star, 34, and Charlize Theron, 35, "have been dating -- for months! They're exclusive, and it's very hush-hush." While the two haven't been photographed together, a witness noticed Reynolds' motorcycle at Theron's home all morning on June 5, then saw the actor exit her house around 3 p.m. -- and she left just minutes later. Has Reynolds (who split from wife Scarlett Johansson last December) found a perfect match? "They're both career-focused," explains the source, "but not in a crazy way." For instance, don't expect to see the stars side-by-side on a red carpet. "She won't go to an event with him," the insider says of Theron, who split with love of nine years Stuart Townsend in 2010. "That's not her style."