Slimmed-down singing star Jordin Sparks is dating a fellow musician: R&B crooner Jason Derulo.

After a lengthy friendship and weeks of flirting via social media, the “It Girl” hitmaker and the former American Idol winner, both 22, have become an item. Jorde and Jase took their relationship public with a belated birthday celebration for Derulo at Philippe Chow in Hollywood on Sunday night. Sparks and Derulo have been quietly dating since headlining a show together in the Bahamas last month, reps for the stars said Monday. We hear it was Jordin’s recent 30-pound slimdown that prompted Jason to see her in a whole new light.Those in-the-know say the pair are smitten with each other and could barely keep their hands off of each other as they dined together over the weekend.

“Jordin would sing to him occasionally through the night in his ear if her head was rested on his shoulder,” a spywitness tells Us Magazine. “It was Jason’s only night in L.A. and the pair were excited to reunite.”

His romance with Jordin is only one of the big developments unfolding for Derulo: His sophomore album, Future History, drops Tuesday.

His romance with Jordin is only one of the big developments unfolding for Derulo: His sophomore album, Future History, drops Tuesday.