Her No. 1 fan! Gwen Stefani kicked off her Just a Girl residency at Zappos Theater at Planet Hollywood Resort & Casino in Las Vegas on Wednesday, June 27, with a very special guest in the audience: her boyfriend, Blake Shelton . The couple — who began dating in November 2015, as Us Weekly exclusively revealed — cozied up together on the red carpet before Stefani, 48, took the stage. Throughout the entire concert, Shelton, 42, held his girlfriend’s youngest son, Apollo, 4, on his lap. (She also shares sons Kingston, 12, and Zuma, 9, with ex-husband Gavin Rossdale .) Gwen Stefani and Blake Shelton’s Sweetest Moments “It was the sweetest thing ever,” an onlooker tells Us. “[Blake] looked like a total father figure to him. He is so smitten with Apollo, and Apollo seemed just obsessed with him. They all seem very much like a family. … [Apollo] was taking some of his snacks and feeding Blake. It was adorable.” Stefani made several references to her relationship with the country...