The Twilight actor, 28, and Australian model and actress, 30, initially ended their one-and-a-half-year romance in early May. "They are back seeing each other, they do have a great time," a source tells Us. "They are trying to be fairly quiet about it, but they're not staying in a bunker or anything. Just a little more discrete."
"It's been a little difficult with him away filming, but he went to her birthday party recently and was such a great guy," the insider adds of the Hercules 3D hunk. "They spent a lot of time together when in L.A."
Lutz also wished Vinson a Happy Birthday on Twitter. "Huge Happy Birthday to the amazing @sharnivinson (Sydney Time ;)) and a Happy Birth Day to the wonderful @narellevinson for bringing such a beautiful soul into this world!" he wrote on July 21.
Lutz and Vinson met during a chemistry reading for Step Up 3D, which led to Vinson landing a role of a street dancer in the movie but Lutz not appearing on screen.
Shortly after they started dating, the actor explained in an interview why they were a good match. "She's a happy person, which really just clicks with me," he explained on Ryan Seacrest's KISS-FM radio show in November 2011. "It's just great to have someone you can smile with all the time. It's really special."