After five months together, the Mumford & Sons singer, 24, popped the question to the Never Let Me Go star, 26. "They're a great couple," a pal tells the new issue of Us Weekly (out now). "Very sweet."
Things first got serious when Mulligan and pal Jake Gyllenhaal caught a secret Mumford & Sons show in Nashville, Tenn. February 7, at the home of band members from The Apache Relay.
"At the end of the night there were just the musicians, Jake, Carey, and the Mumford boys," an insider told Us at the time. "We had some pizza, and just played music. Jake picked up a guitar and Carey joined in on 'Amazing Grace.' Marcus and Carey seemed really friendly."