After weeks of rumors, Ashlee Simpson has taken her romance with Evan Ross public. The newly minted squeezes cozied up at a fashion event in New York on Tuesday night. The occasion was the launch of theJessica Simpson Collection Fall 2013 campaign, with Ashlee filling in for her big sis, who has her hands full with her month-old son, Ace. Ashlee, who wore a turquoise dress from Jessica's collection, posed and held hands with Evan, who's the offspring of Diana Ross. According to Us, the two have known each other for about a decade and have many mutual pals. "It helps that they were friends first," explains a source. "They have a long bond. They already know each other really well." Ashlee, who is mom to 4-year-old Bronx Mowgli with her ex-husband, Pete Wentz, previously dated "Boardwalk Empire" actor Vincent Piazza.