Stacey Earle and Mark Stuart come from the folk-roots tradition that allows married couples -- think Gillian Welch and David Rawlings, Buddy and Julie Miller, Robin and Linda Williams, and maybe even Sonny and Cher -- to work and prosper together. Stacey, Steve Earle's youngest sister, met Mark in the mid-'90s, when he was playing with her brother's Dukes. The couple's almost-shy banter between songs is one of the highlights of its latest release, Must Be Live, which captures both its heartfelt, gentle songs and its humor-filled self-awareness of what it means to be a couple onstage. Both are strong songwriters, but together, they're even better, with Earle's distinct Texas twang and Stuart's fluid, gorgeous guitar connected at the hip. They write, sing and talk about each other with a candor and facility that offers hope not only to singing couples but also for marriage in general.