The freshly-formed couple arrived hand-in-hand at a CMA after-party ... thrown by Warner Bros. Music in Music Square.
Gwen's clutching a glass of white wine while Blake's got some sort of iced drink in his Styrofoam cup.
As we reported, Gwen decided at the last minute to accompany Blake to Nashville. We're told the relationship is new ... just days old.
Judging from the stars we talked to after the CMAs, country approves.
Our sources say they'll spend a few days in Nashville before returning to L.A.