Selena Gomez Arrives at the Metropolitan Museum of Art Costume Institute Gala Benefit in New York
Actress Selena Gomez arrives at the Metropolitan Museum of Art Costume Institute Gala Benefit celebrating the opening of "Charles James: Beyond Fashion" in Upper Manhattan, New York, May 5, 2014.REUTERS

Selena Gomez is apparently not too happy with Justin Bieber's closeness to Kylie Jenner, and reports have it that this was what caused Gomez's falling out with the Jenner sisters soon after hanging out at Coachella music festival.

Recently, Bieber posted a selfie of him with Jenner on his Instagram account, and this had made matters worse with his on-again, off-again girlfriend, who feels Jenner is a pathetic Bieber groupie.

"Selena was not happy that Justin posted a selfie with Kylie. She thinks Kylie is desperate for attention and is a pathetic Justin Bieber groupie," an insider told HollywoodLife. "It was obvious at Coachella that Kylie had the biggest crush on Justin, she was flirting then and continues to flirt."

The source noted that Gomez will lose all respects for Bieber if he starts to date Jenner, whom he took as his date for the Floyd Mayweather fight in Las Vegas on May 3. Reportedly, the duo even had dinner together at the Hard Rock Hotel, sparking speculations that Bieber might be interested in Jenner.

Meanwhile, Gomez reconnected with former girlfriend Taylor Swift at the Met Ball and the "Come and Get It" singer posted online an adorable video of them hanging out together at the event.

"And during.. sometimes you wanna just be you with someone who knows all your secrets," she captioned the video.

Swift and Gomez were said to have been at loggerheads over the 21-year-old's decision to date Bieber. Swift has been open about her disapproval of their relationship, at one point she was even photographed making faces at him.

But with Bieber now back to his "bad boy" ways, Gomez understands why Swift was protective of her.

"Selena was the one who initiated the reunion with Taylor at the Met Gala. Selena contacted Taylor before the event and told her how excited she was to see her," another insider told HollywoodLife. "She has totally forgiven Taylor for not wanting her to date Justin and now fully understands why Taylor was being so protective."