Sofia Richie and Justin Bieber split up after one month

Justin Bieber and Sofia Richie have been dating each other for a few months. Photo / Getty Images

Sofia Richie and Justin Bieber have split up after a month-long romance.

According to TMZ, the relationship was not that serious to begin with. The 22-year-old Sorry hit maker and the 18-year-old Yeezy model have not been photographed together since their Mexican getaway on August 29, according to the href="http://www.dailymail.co.uk/tvshowbiz/article-3797211/Sofia-Richie-Justin-Bieber-called-quits.html" target="_blank">Daily Mail.

On Saturday the blonde partied at The Nice Guy and earlier in the day she appeared somber at the treats! 4th annual White Party in Malibu. Her plus one was 1OAK and Beacher's Madhouse co-owner Darren Dzienciol.

Meanwhile, the Where Are You Now? singer was spotted in Cologne, Germany on Monday.

Their romance got off to a roaring start in August as they frolicked in Laguna Beach, California. By mid-month they were holding hands in Tokyo.

And for her 18th birthday in late August, they hit The Doheny Room in Hollywood.

A trip to Cabo San Lucas, Mexico, followed where they got their PDA on while hanging out on a yacht.

Ever since then they have not been seen together, though she has been caught wearing his Purpose tour sweatpants.

Adding to the drama is the UsWeekly report that Justin has been trying nonstop to call his ex Selena Gomez, but she has switched her phone number and has asked pals to not give the Baby crooner her new digits.

Selena Gomez has been ignoring many phone calls from her ex boyfriend Justin Bieber. Photo / AP

The Same Old Love singer has been taking a break from her Revival tour ever since she spat with Bieber - her beau from 2011 until 2015 - on social media over his decision to post loved-up photos with Sofia.

She explained though that she needed time to herself as she fights the anxiety and depression that comes with Lupus.

At the treats! event, which was sponsored by Stella Artois, the teen wore a white shirt that said OFF on the collar - maybe a sign she had split with Bieber? - and white high top sneakers.

The blonde also modeled gold-rimmed round sunglasses that seemed to have multi colors on the lens.

Sofia Richie attends the Treats! Magazine 4th Annual White Party, wearing a dress that says OFF. Photo / Getty Images

And on her shoulder was a long-strapped purse.

She posed by the balcony that overlooked the Atlantic Ocean.

Also at the outdoor event was Matt Bellamy, who used to be engaged to Kate Hudson, and his girlfriend Elle Evans.

Matt looked sporty in a white shirt and jeans while Elle wore a thigh-exposing white dress and heels.

The Muse rock star was also seen posing with treats! editor Steve Shaw, who broke his own party theme rule with a black belt.