PHOTOS: Hollywood's biggest flirts Murray, 32, and Roemer, 29, currently work together in Crackle's TV series costar Nicky Whelan.
The couple made their red carpet debut at the Lucky Brand Flagship Store opening in Beverly Hills in October 2013.
First, it was released as a sneak peek on American Idol prior to Cook's performance of "Come Back to Me" and then it was released through AT&T later the same day.
Cook stated that he had to learn to sing the song backwards.
"Come Back to Me" was written by Espionage, the Norwegian songwriting and music production team consisting of Amund Bjørklund and Espen Lind, along with Zac Maloy.
The song was produced by Grammy winning producer Rob Cavallo.
Murray became engaged to his One Tree Hill co-star Sophia Bush in May 2004.