NIKKI & RICH A California girl and New York guy make beautiful music together As far as mea culpas go, “Next Best Thing,” the debut single by pop duo Nikki & Rich, isn’t particularly remorseful. Over malt-shop piano and doo-wop backing vocals, singer Nikki Leonti tells a heartbroken ex it was boredom that led her to stray. “It’s my fault, I’m the one to blame,” she coos, callous and cavalier. “Shame on me and my man-eating...