Rachel McAdams has found herself a leading man in the romance department.
"It hasn't been long," says an insider. "But it's serious."
RELATED: Celebs who had breakup makeovers
The two have apparently known each other for years, but they grew closer on the set of the HBO drama.
"I don't know if it's full-blown love yet, but they talk constantly," a second source told the magazine. "They're really into each other. She talks about him all the time!"
RELATED: Famous behind-the-scenes feuds
In the past, Rachel has said that finding love on the set is inconvenient. But, that hasn't stopped her, having dated Ryan Gosling, her costar in "The Notebook." She reportedly dated "Southpaw" costar Jake Gyllenhaal, as well.
"A set may seem like a good place for romance, but I don't think it's very conducive; it's too distracting," she previously told Glamour. "Every relationship I've had with a coworker comes after the fact."