Demi Lovato and Wilmer Valderrama

Demi Lovato and Wilmer Valderrama have separated following a rocky few months, which included the Sonny with a Chance star checking into a treatment center, according to the New York Post.

Demi Lovato, like Catherine Zeta-Jones, has bipolar disorder

The 18-year-old Lovato, who completed a three-month rehab stint for "physical and emotional issues" in January, was reportedly dating the That '70s Show alum before and after her treatment. A source told the Post that their age difference — more than a dozen years between them -- "meant they were in completely different places in their lives." Valderrama, 31, has been previously linked to Lindsay Lohan, 24.

Demi Lovato is leaving Disney's Sonny with a Chance

The news comes on the heels of Lovato's mother, Dianna Hart de la Garza, being admitted into rehab. The source told the Post that after supporting Lovato through her recent troubles, it's now her turn to "deal with her own issues."

Reps for the actress/singer did not immediately respond to TVGuide.com's request for comment.