Earlier this week, the New York Post's Page Six was first to report on the 32-year-old actor's new relationship with Miller, 23. The two were spotted having lunch together last week at downtown Manhattan eatery the Dutch in New York City, and were later seen "making out" at Cold Process Coffee & Tea.
A source explained to Us of their lunch date: "They came in as a couple. They were very quiet and private, Jake seemed into her. They were both dressed down and not easily recognizable."
A second insider adds, "They met at their gym. It's very new. They really like each other, but it's new."
But the "End of Watch" actor doesn't seem to stay in relationships for very long. Last summer, he had a brief romance with Minka Kelly, and before that dated Taylor Swift from three months in late 2010. Gyllenhaal was also in a relationship with his Rendition costar, Reese Witherspoon, from 2007 to 2009.