Rachel McAdams and Taylor Kitsch's friendship has heated up since wrapping production on "True Detective" season two. The co-stars are now dating, according to Us Weekly.

"It hasn't been long," an insider told Us Weekly. "But it's serious."

McAdams and Kitsch were first spotted together at West Hollywood's Osteria Mozza on June 2. The couple was longtime friends before working together on the HBO drama, but "they grew closer on set."

The 36-year-old actress recently sparked romance rumors with her "Southpaw" co-star Jake Gyllenhaal. She famously dated her co-star Ryan Gosling from "The Notebook."

Kitsch also endured a recent break up with his girlfriend, fitness instructor Jennifer Welch. The 35-year-old actor has now worked his magic on McAdams.

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

So why did McAdams choose Kitsch over her other "True Detective" co-stars?

Vince Vaughn has been married to his wife Kyla Weber since 2010 and Colin Farrell hasn't dated anyone in four years.