Justin Bieber and Selena Gomez might be on the rocks again after reports claim the troubled singer cheated on his lady during SXSW festival.

An insider source told Star magazine he "couldn't resist" the temptation to hook up with a groupie.  According to the gossip magazine, Bieber has had issues with staying faithful to Gomez in the past, allegedly hocking up with an groupie during while the "Stars Dance" singer was filming a commercial on March 11.

"It's a toxic and dangerous situation," the source told Star.

Gomez's loved ones are concerned Bieber's alleged infidelities will cause take her over the edge, causing another trip to rehab for her emotional issues.  Gomez never confirmed if her rehab stay was due to her tumultuous relationship with Bieber, but  did open up about her struggles during the We Day conference in Oakland, Calif. in March.

"I'm surrounded by people who are supposed to guide me and some of them have and others haven't," she told the audience. "They pressure me, [saying] 'You gotta be sexy, you gotta be cute, you gotta be nice, you gotta be all these things.' You can all relate. You all have pressure that you have to deal with every day - with school, with work, with friends, with parents, with family. They tell me what to wear, how to look, what I should say, how I should be."

"Until recently, I had given into that pressure, I lost sight of who I was," she revealed, clearly getting choked up. "I listened to opinions of people and I tried to change who I am because I thought others would accept me for it. And I realized I don't know how to be anything but myself."

Do you think Justin and Selena are right for each other? Let us know in the comments section below.