Gwen Stefani [1] and Blake Shelton brought their supercute romance to the Billboard Music Awards [2] in Las Vegas on Sunday night. The two showed off their obvious chemistry [3] when they took the stage to perform their duet, "Go Ahead and Break My Heart." [4] In addition to Gwen looking gorgeous in a floor-length gown and neutral makeup, she couldn't stop staring at Blake while they sang. For more of their sweet relationship, see the cutest things they've said about each other [5]!