Justin Bieber 'cheating on' Selena Gomez with groupies, Jelena romance 'toxic?' Singer 'can't resist' sexy fan hook-ups behind girlfriend's back

Maybe Justin Bieber and Selena Gomez should just stick to being single for awhile.

The two pop superstars reconnected back in March, sparking rumors that a Jelena romantic reunion would soon follow. But apparently, the 20-year-old "Believe" crooner enjoys his freedom when it comes to the ladies.

According to the infamous gossip tabloid Star, the Biebs "hooked up" with a groupie shortly after trying to make things work with Gomez. Hollywood Life reports that when the "Come & Get It" beauty flew out to NYC to shoot an Adidas commercial, Bieber allegedly slept with an unidentified fan in LA.

Now, friends are worried that Gomez might get dragged down (again). Especially because she keeps on forgiving her ex-flame.

"He couldn't resist... It's a toxic and dangerous situation," an alleged source reveals.

Meanwhile, Jelena tries to keep their romance alive with sexy flirting via text messaging and Skype:

"They're both so into their images and turning each other on. It's starting to spill over into their public selfies, which are getting sexier and sexier," another insider for OK! magazine explains. "They're both so bad for each other, as they really bring out each other's daredevil side. Right now they're totally in lust and, as usual, pushing their luck by filming their bedroom activities."

Rumors suggest that Jelena has reconnected, but they're not officially back together. And perhaps that's for the best right now - both are still so young!

So how about it, Mstars fans. Did Bieber really cheat on Selena (again) with a one-night stand - and do you think the young Hollywood relationship is truly "toxic?"