Chrissy Teigen and John Legend have been through a lot in their 12 years of marriage - but the singer says the key to their successful relationship is simple. "Just support each other and love each other. Have each other's back," Legend, 46, told Us Weekly exclusively at the Black Music Action Coalition (BMAC) Gala in Los Angeles on Thursday, September 18. "We've been through it all together - so much joy, but also pain and challenge and grief.