Justin Bieber and Selena Gomez are one of the most popular young celebrity couples out there these days. But there may be trouble in paradise, according to a new report that suggests that they have had a rocky road as of late.

The Biebs and Gomez have apparently broken up multiple times in the past several months, according to an exclusive new report by gossip website TMZ.

Justin Bieber and Selena Gomez -- who have been an item for about one-and-a-half years -- broke up as recently as last week, sources in a position to know told TMZ, but they are now at least somewhat back together.

TMZ says its sources say the famous duo are back together, but that they are not solid at the moment.

Pop singer Justin Bieber, though still only 18 years old, is one of the most popular individuals in the world, and he is the star of the world's all-time most-viewed YouTube video in Baby, his breakout smash hit that has been viewed more than 755 million times.

And he is also probably one of the most-scrutinized as he has become one of the most popular people on Twitter, where his account has more than 24 million followers.

And his (apparently on-again, off-again) romantic interest, Selena Gomez, has also found massive popularity.

Best known for playing the part of Alex Russo on the hit kids' show Wizards of Waverly Place, Gomez has a huge fan base of her own, and has also built a massive presence on Twitter, where nearly 12 million users follow her account.