The couple shared the good news on Twitter Thursday with a selfie, and his and her tweets: "I'm engaged to her!" and "I'm engaged to him!"
The Cougar Town star and McDaid, who plays piano and guitar for the Irish-Scottish indie band, have been together for only six months, but the pair has already collaborated on Cox's film, Just Before I Go. Snow Patrol wrote three original songs for the movie, which Cox directed.
Cox, 50, was previously married to David Arquette, with whom she shares custody of their 10-year-old daughter Coco. This will be the first marriage for McDaid, 37.
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Im engaged to him! pic.twitter.com/gsFtZkb3Bk