The couple was photographed on Sunday night in Los Angeles while going to the cinema, but the actress was not wearing a ring to mark their engagement.
“There’s no ring, but they are committed,” the mag’s source stated.
Wedding rumors surfaced this summer when a source cited by Us Weekly claimed that Theron and Penn planned “to get married very soon.” The publication also stated that they intend to adopt a baby after the ceremony.
The Oscar-winning actress is already a mom to son Jackson, 2.
This year, Theron opened up about marriage in an interview with the June issue of Vogue.
“Let’s put it this way: I never had the dream of the white dress,” she said.
“And watching other people getting married? I think it’s beautiful for them, but to be quite honest, usually I’m sitting there just devastated. It’s supposed to be this night of celebrating love, and all you see is a couple separated all night making sure everybody else is okay. It just looks like a lot of work. And as you get older, you start sifting through the stuff that really matters,” she added.
The South African beauty also opened up about her relationship with Penn.
“Sean and I have known each other for 18 years. We were just really good friends. And it’s been slow going because you are aware that you could screw that up and lose it,” she told the mag then.
“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,” she added.
Dating rumors about the two circulated last December when they were spotted together in Hawaii, at the beach.