Who knew Vince Vaughn was such a romantic?

In an interview on The Ellen DeGeneres Show (airing Monday), the Couples Retreat star, 39, reveals that he proposed to girlfriend, Canadian real estate agent Kyla Weber, this past Valentine's Day.

But he says he talked about it with her first, just to make sure she'd say yes.

"Have you seen these things where these people ask people to marry them in really public ways and then the people say no?" he says. "You think they would have had a little talk before they went to that extreme. Then you start to wonder, 'Did they go to such a big public display to corner the other person so they couldn't say no?'"

See unlikely celeb couples who found love

"I knew we had talked about it. I knew we were both kind of in agreeance with it," he goes on. 

Then, he says, it became a question of "'When do you ask?'"

When Valentine's Day rolled around, "I figured this is not a ship to be missed because I will not forget this date," Vaughn says. "So Valentine's Day was the day that I asked her."

See celebs who've had bad luck at getting engaged

He says it worked out great "because it would have been kind of weird to have talked about it and then skipped Valentine's Day."

See photos of your favorite stars in wedding dresses

Vaughn - who previously dated Jennifer Aniston - is "very happy" with Weber, whom he met through a friend a year-and-a-half-ago. "She makes me laugh. She is wonderful. I'm just thrilled."

Get more Us! Follow us on Twitter, Friend us on Facebook, Subscribe to Us Weekly