 While recording her debut studio album in 2005 , Rihanna met Ne @-@ Yo for the first time , but they could not collaborate on the album . She wanted to work with him since she heard " Let Me Love You " ( 2004 ) by Mario , which Ne @-@ Yo wrote . When the production for A Girl like Me started , she considered working with him . She said , " So for the second album , I was like , ' You know what ? I have to work with that guy Ne @-@ Yo . ' So we went into the studio and we started working on this song . " Ne @-@ Yo and Norwegian production duo Mikkel S. Eriksen and Tor Erik Hermansen collectively known as StarGate wrote " Unfaithful " , which Rihanna said was " new ground for [ her ] " because it was a ballad . It was produced by StarGate while Debbie Mounsey served as a production assistant . " Unfaithful " was recorded by Eriksen , Al Hemberger , Malcolm Pollack and Tiger Stylz at Battery and Avatar Studios in New York City , Loft Recording Studios in Bronxville and Digital Insight Recording Studios in Las Vegas . It was mixed by Phil Tan and Makeba Riddick provided the vocal production . 
