The "Sorry Not Sorry" songstress is reportedly "upset" she wasn't invited to the three-day extravaganza that took place in Chopra's home country of India.
"Demi was so upset that she wasn't invited to Nick's wedding after everything that they have been through together," a source told Radar Online. "She has been his best friend forever."
But the source said that Jonas had a reason why he and Chopra didn't invite her to their nuptials. "Nick did not want Demi's fame-wagon to overshadow him and Priyanka's special day. Plus, he wasn't certain that she was still going to be out of rehab at the time of his wedding."
Radar reported that Lovato even unfollowed Jonas on Instagram last week. As of press time, Lovato does not follow him. As previously reported, she had also unfollowed some of her other celebrity friends on the social media platform. Including Jonas, she also unfollowed Selena Gomez and Iggy Azalea, all of whom have been close to her at some point. She still follows Jonas' brothers Joe and Kevin.
A source told Entertainment Tonight that Lovato unfollowed her friends because she wants to "focus on herself" and "avoid any difficult relationships."
"She needs to surround herself with those that support her goals and to stay away from any negativity," the source said. "Demi has come a very long way. She's grown emotionally and matured a great deal through this process. She realizes there is no quick fix and has accepted the fact she needs to take this one day at a time. She still has a sober companion and she has built a very strong support group."
Lovato has used social media sparingly since completing a 90-day stint in rehab following an overdose in July. At the end of October, her mother said she was 90 days sober.
She shared a rare selfie on Instagram following her marital arts workout this week. "Sweaty, messy, jiu jitsu hair.." she captioned the sweaty selfie.
Her followers were overjoyed to see her back on social media.
"I'm so proud of you Demi!!!! Keep fighting sis!! Blessings," one user commented on the photo.
"So great to see you again, you look soooooo Gorgeous!!!!" another user wrote.
The singer has reportedly focused on staying physically and mentally healthy following rehab.
"Working out is cleansing for her mind, body and soul," the insider told Us Weekly. "It keeps her on track, focused and feeling good."