Broadway is still buzzing about a romance between “Smash” beauty Megan Hilty and Nick Jonas. Sources say they’ve been “seeing a lot of each other” since Jonas, currently starring in “How To Succeed in Business Without Really Trying,” guest starred on the NBC show. Jonas and Hilty were seen dining together at Cafeteria in Chelsea last month. But a source, noting that Megan is 31 and Jonas 19, tells us, “They are just friends.” Reps for both declined to comment.