Selena Gomez and Mandy Teefy are reportedly at war due to Gomez's reunion with her on-again, off-again boyfriend, Justin Bieber.

According to a new report, Gomez and Teefy have been feuding with one another ever since Gomez reconciled with Bieber in late October of last year. Recently, Gomez allegedly began taking aim at her mother with mean-spirited insults.

Gomez and Teefy “have been going back and forth with each other over Justin, and Selena doesn’t want to hear it anymore from her,” a source close to the "Wolves" singer revealed to Radar Online on Jan. 10. “So after Mandy came for her once more, Selena hit below the belt with a nasty insult over her failed relationship with Selena’s father. That was the last straw.”

Following their nasty fight, Gomez and Teefy reportedly stopped talking to one another and even unfollowed each other on social media. However, the dispute between them hasn't led to any drama between Gomez and Bieber. Instead, it has seemingly brought them closer as their romance begins to heat up.

As the Radar Online insider explained, Gomez is beginning to not care what her mother thinks of her relationship -- or what anyone has to say about her rekindled romance with Bieber. In fact, regardless of what anyone believes, Gomez is planning to continue to do what she wants and follow her heart.

Although Gomez and Bieber have been doing their best to keep their recently reconciled relationship under wraps, rumors are swirling in regards to potential discussions for a wedding.

“She is convinced that he is the one, and that they will get married and stay together forever,” the source said.

Gomez and Bieber first stepped out with one another in late October. However, because Gomez was still dating The Weeknd at the time, no one thought too much of their time together. Then, just days later, Gomez and The Weeknd split up and Gomez and Bieber went on to confirm their romance while kissing one another in Los Angeles during an ice hockey game.

Since rekindling their romance at the end of last year, Gomez and Bieber, who recently celebrated New Year's Eve with one another in Mexico, have faced a number of allegations of possible split and plans to wed but thus far, none of those reports have been proven true.