The former That '70s Show star, 33, popped the question on Saturday.
Phillips, 28, was coy when asked if a wedding was in the works.
"It's not a yes; it's not a no," she told Us last April. "It just sort of is, you know?"
The two, who appear in the upcoming indie Wake, also just shot two films together: Made for Each Other and The Bridge to Nowhere directed by Blair Underwood.
How do they balance work and romance?
"I don't know -- we just do," Phillips told Us.
The trick to staying together? Not blabbing about their relationship.
Asked if she had any love advice she told Us: "I wish I did. This is my hidden tip -- not talking."