Charlize Theron, Sean Penn Secretly Engaged: Get the Details!

Sean Penn and Charlize Theron coupled up last year and have never looked back.

While not officially "engaged," per se, the dashing couple are otherwise in it to win it, a source tells E! News. "They have made a commitment to be together for the rest of their lives," the source says. "They are discussing when and where they will have a wedding."

So though Theron hasn't been rocking a so-big-you-can-see-it-from-space diamond like some stars, it sounds as though Penn has proverbially put a ring on it.

The Oscar winners have been dating for more than a year now, their newly romantic relationship first becoming apparent when they spent Christmas together last year in Hawaii and both returned to L.A. on New Year's Day. They've been pretty inseparable ever since, hiting their first red carpet as a couple in March and one rarely attending an event without the other ever after.

Penn has also seemed to hit it off with Theron's son, Jackson, the trio often spotted together running errands like any family.

And the devoted duo didn't even have to leave each other for work this fall! Penn's latest directorial effort, The Last Face, stars Theron and Javier Bardem as aid workers in Africa who meet in the midst of social, political and humanitarian unrest. They filmed the drama in South Africa.

It doesn't have a release date yet, so maybe director and star will reach the altar before the film reaches theaters.

Earlier this year, Theron called their relationship "effortless."

"Sean and I have known each other for 18 years. We were just really good friends," she said in Vogue's May issue. "And it's been slow going because you are aware that you could screw that up and lose it. We had to think about it. But at the end of the day, it was somewhat effortless. It just kind of naturally happened, and before I knew it, I was in something that was making my life better—the people who really love me can see the effect it has had on me."

Penn has been married twice, to Madonna for four years in the 1980s and then to Robin Wright, with whom he has two children, from 1996 until she filed for divorce in 2009. Theron was engaged for years to Irish thesp Stuart Townsend before they broke up in 2010.