First Published: January 31, 2014 5:21 PM EST Credit: Twitter

LOS ANGELES, Calif. -- Demi Lovato took to Twitter to wish on-again, off again boyfriend Wilmer Valderrama a very happy birthday — and the singer was incredibly complimentary to her sometime beau.
“To the funniest, most inspiring, incredible man I know.. @WValderrama - thank you for helping me get through my darkest moments..,” Demi Tweeted on Thursday, along with a photo collage of the pair. “You truly are a light to this world and to my life.. Happy Birthday!!!”
The 21-year-old singer also sparked rumors that she may be engaged to Wilmer, 34, when she Tweeted a photo of herself wearing a ring on her wedding ring finger.
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However, a rep for the former “The X Factor,” judge told Us Weekly that Demi’s ring is not an engagement sparkler.
In August 2013, Wilmer wished Demi a happy 21st birthday on Twitter.
“I’ve been so proud of the strength & commitment you’ve gained 4 life, keep inspiring us all! Happy birthday my @ddlovato!” the actor wrote. “With & by u always.”
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