Demi Lovato has had a career full of highs, but the singer has also battled some demons in the form of substance abuse and bipolar disorder. Now, she’s celebrating three years of sobriety and took to social media to thank her boyfriend, actor Wilmer Valderrama.

The couple each posted sweet notes to one another on Instagram, with Valderrama praising Lovato for realizing that her life was worth something.

“Today, we lay another stone together..It is now 3 years since you said: I am more important then any past, demon, disorder or addiction. Where you decided that YOUR life was worth living while loving yourself.. And I’m sure glad you did… I knew then the woman you’ve become now. I am proud and honor to be front row to see the world you are about to change,” Valderrama wrote.

Demi quickly responded with a post of her own on the image-sharing site.

Today, we lay another stone together.. It is now 3 years since you said: I am more important then any past, demon, disorder or addiction.. Where you decided that YOUR life was worth living while loving yourself.. And I'm sure glad you did… I knew then the woman you've become now.. I am proud and honor to be front row to see the world you are about to change. I love you Demi.

A photo posted by Wilmer Valderrama (@wilmervalderrama) on Mar 15, 2015 at 12:59pm PDT

I wish I could put into words how grateful I am for this man right here. But my love has grown to a level that words could never possibly express how much this man completes me. He's loved me the way I never thought I deserved to be loved and with this day marking my 3rd year sober… After sharing my ups, putting up with my downs and supporting my recovery… he still never takes credit and I want the world to know how incredible his soul is. I really wouldn't be alive today without him. I love you Wilmer

A photo posted by Demi Lovato (@ddlovato) on Mar 15, 2015 at 11:26pm PDT

Lovato and Valderrama have been together for quite a while now, and sources at Hollywood Life say they are close to getting married, although nothing has been confirmed by the couple.

“They always talk about marriage, and they are definitely going to get married, but a timetable has not been determined for when that will happen. There is no pressure and it could happen in 2015, but it could easily happen in 2020. Its coming down to when they want to have kids, they want to do everything all at once,” the source said.