Nashville Anthems: Dissecting 80s & 90s Country Music

Dissecting "I Cross My Heart" by George Strait

We follow one "Pure Country" hit with another: 1992's "I Cross My Heart".  George Strait doffs the pyrotechnics (or something like that) and gets intimate in this one, but how do these rolling harmonic and melodic hills frame this speaker's specific message of commitent?  And what about that key change??