Demi Lovato and Selena Gomez have been best friends since their Barney and Friends days 14 years ago. They have helped each other through rough patches in the past with personal and relationship problems.

This time however, rumors have surfaced of trouble in paradise. Lovato, 21, prompted these speculations when she unfollowed Gomez, 21, on Twitter. The "Really Don't Care" singer then supposedly dissed her ex-friend. She posted a collage of photos with the text "Swimming away from your bulls***. Bye b*tch," which fans observed was meant to throw shade at Gomez.

The "Scyscraper" hitmaker eventually deleted the tweet a few minutes later. That still didn't deter both girls' fans from wondering about the apparent fight.

A source reportedly told Hollywood Life that the feud was centered around the "Love Song" singer's rocky relationship with on-again boyfriend, Justin Bieber.

Lovato had helped her best friend in the past, giving her relationship advise and supported her after breaking up with the troubled Canadian singer. The Hollywood Life source revealed that the once patient Lovato is now "pissed" at Gomez being hurt over and over again by Bieber.

"Demi doesn't need any extra drama, she's learned from her own recovery to lose the people that bring her down and Selena is to much of a headache," the insider reportedly said. "The unfollowing of Selena is sending a message that Demi is pissed. She is sick of Selena's boy-who-cried-wolf mentality."

The source also said that the "Heart Attack" singer seriously got annoyed with the "Come And Get It" hitmaker because "Selena refused to listen to Demi's advice."

It has only been a few months since Gomez thanked Lovato in her acceptance speech for her Young Humanitarian Award at Variety's unite4:humanity gala. Lovato has also been very vocal about her friendship with the fellow singer, telling E! Online, "I love her!"

Lovato's representatives refused to comment on the issue as of this moment.