Watch: Miranda Lambert Reacts to Fans Disappointed She's Opening for Morgan WallenKacey Musgraves and Miranda Lambert's relationship has been a slow burn. The "Golden Hour" singer shared insight into their dynamic after Miranda recorded the 2011 song "Mama's Broken Heart," which Kacey cowrote before launching her own solo career. "It was gonna be my first single and I loved the song so much," Kacey told NPR Music in an interview published March 11.