Wilmer Valderrama Constantly Visits Demi Lovato in Rehab

Demi Lovato is still in rehab -- nearly 2 months after her overdose -- and one person has put his life on hold to be a constant presence -- Wilmer Valderrama.

TMZ has learned Demi quietly transferred from a rehab center on the East Coast to another facility that is world-renowned for its addiction programs. She's been at that facility for more than a month, and Wilmer has flown there several times during visiting days to be with her.

Several people in a nearby town tell TMZ, they've seen Demi and Wilmer at a local Starbucks several times, and it appeared to people in the shop they were boyfriend/girlfriend.

We don't know if they're back together ... what we do know is that Wilmer put everything on hold when Demi almost died from an opioid OD on July 24 and was a constant presence at the hospital, where she spent nearly 2 weeks.

Demi and Wilmer were together for 6 years and split back in 2016.

As for rehab, the facility offers intensive, long-term treatment for drugs and alcohol and is very much a group program. In fact, Demi was also seen several times at the Starbucks with other patients from the rehab facility.