Justin Bieber is "driving himself crazy" over on and off again girlfriend Selena Gomez's seemingly budding romance with Zedd.

HollywoodLife.com reports an agitated Bieber has taken to having his pals regularly check all of Gomez's social media platforms so he can keep an eye on how close she might be growing to Zedd.

"Justin can't stop thinking about Selena and Zedd," a source said. "He's become obsessed with them as a couple ... with 'what ifs' and 'should haves.' He feels like he royally screwed up and has maybe lost Selena for good. This is the first time he's ever admitted that possibility. He wants to know what Selena and Zedd talk about and how serious they are."

The 20-year-old "Baby" singer and the first artist to ever have seven songs from a debut recording appear on the Billboard 100 and the 22-year-old "Come & Get It" crooner have dated on and off since at least around Valentine's day 2011, when they took to the red carpet together at a Vanity Fair Oscar Party. The couple publicly split for one of the first times in 2012, but since then, they've had more stops and starts in their volatile relationship than a rollercoaster.

Several media outlets have previously reported the couple reunited in 2013 after Bieber surprised his lady with a single red rose for her 21st birthday. Not long after that, the two were vacationing in St. Martin together before another public blowup drove them apart.

For what it's worth, Gomez and Zedd's dealings haven't seemed to be nearly as stressful. The two were recently spotted enjoying a bowling date night together in Atlanta.

Still, there may still be hope for Bieber. Sources close to Gomez have admitted that one of newest tunes, "The Heart Wants What It Wants," seems an obvious nod toward Bieber.