Did love bloom on the True Detective season two set?!

Rachel McAdams, 36, and Taylor Kitsch, 34, are reportedly dating and it's "serious,"Us Weekly is reporting. The two Canadian stars have been "friends for years," says a source, and "grew closer on set."

According to an eyewitness, McAdams and Kitsch definitely looked close on set, and hung out together in between scenes. They were "together during breaks laughing and giggling," the eyewitness tells ET. "They seemed very comfortable with each other. [They were] causal, like they were enjoying just hanging out."

WATCH: Ryan Gosling Tried to Kick Rachel McAdams Off  'The Notebook'

"I don't know if it's full-blown love yet, but they talk constantly," another source tells Us. "They're really into each other. She talks about him all the time!"

The pair were seen dining together at Osteria Mozza in West Hollywood, Calif., last month, which set off the dating rumors.

Rachel's last high-profile romance was with actor Michael Sheen, who she split with in 2013 after more than two years together. Kitsch was last linked to fitness instructor Jennifer Welch.

In a June interview with Elle, Kitsch talked about his troubles with dating.

"You sacrifice so f**kin' much [as an actor]," he told the magazine. "How do you build a relationship with a gal and then tell her, 'Hey, I gotta do press all over the world. I expect you to have the same feelings you have now in eight weeks.’ And that's not me playing the violin. It's my choice. But it better be worth sacrificing for."

... Perhaps he found someone who obviously understands!

WATCH: Vince Vaughn Talks 'True Detective' and the Story Behind the Hilarious Stock Photos

Watch the video below for more on the handsome former Friday Night Lights star, including his revelation that he was actually homeless and sleeping on the subway in New York City before his big break.