Selena Gomez allegedly thought Justin Bieber would propose to her during their trip to Paris last week.

A source told the HollywoodLife.com: "The fight started because Selena was expecting him to propose on their trip and he didn't. She was disappointed and when she brought it up he flipped out."

The couple rekindled their romance last month after the 'Come & Get It' hitmaker dumped the pop star, 20, for allegedly flirting with Kylie Jenner, 17, at the Coachella Valley Music Festival in California in April.

The source added: "The thing is, when they got back together he told her he was already ring shopping, it's one of the reasons she agreed to take him back.

"Selena wants that security, she is ready to take that step with him and he promised her that he was too, but he was just leading her on."

The turbulent pair sparked rumours they'd parted ways once again when Justin was spotted enjoying a boozy lunch date with Kylie's sister Kendall, 18, while Selena was taking in the stunning sites with her pals.

Further speculation was fuelled last week when Selena 'unfollowed'

Justin on photo-sharing site Instagram and started posting cryptic messages on Twitter.

She wrote: "Sometimes we think we aren't good enough. But then I realize when I think I'm alone I have God. We have to learn the hard way sometimes. (sic)."