Justin Bieber's relationship with his girlfriend Selena Gomez is reportedly on the rocks.

The 18-year-old Canadian pop star and the 19-year-old Hotel Transylvania actress have been dating for around a year and a half.

According to TMZ the pair are experiencing a rough patch in their romance.

A source told the website that Justin and Selena "have broken up multiple times in the last few months."

The couple are rumoured to have split as recently as last week.

"[They're not] solid," the source revealed.

Justin spoke in June about what he does to keep his sweetheart happy.

"I like to take the time and do special things, and I think that's what, you know, girls like to have that sense of security," he told Entertainment Tonight.

He also commented on what women he finds incredibly attractive at the moment.

"Beyonc. She's so sexy. I'm in love with everything about her," he told Q magazine in an interview this month. "I think I'm a butt guy. I just like butts. I'm attracted to them. Do I have any favourites? Nicki Minaj has got a nice one."