@ddlovato / Twitter 1 / 6
@ddlovato / Twitter 1 / 6

Public display of birthday affection! Demi Lovato took to Twitter on Thursday, Jan. 30 to wish on-again, off-again rumored boyfriend Wilmer Valderrama a happy 34th birthday with a sweet message.

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"To the funniest, most inspiring, incredible man I know . . . @WValderrama -- thank you for helping me get through my darkest moments," Lovato, 21, wrote. "You truly are a light to this world and to my life . . . Happy Birthday!!!!"

The Twitter PDA, however, only fanned the flame on earlier rumors that the pair are engaged. On Wednesday, Jan. 29, Lovato shared a pic of herself wearing bling on her ring finger, but her rep told Us Weekly Thursday that it's not an engagement ring.

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The "Skyscraper" singer and That '70s Show alum first hooked up in 2010. Their relationship status has remained unclear since then, but they haven't kept their close friendship a secret.

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Last August, Valderrama wished Lovato a happy 21st birthday in a heartfelt message 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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