Justin Bieber called things off with Sofia Richie because the singer 'doesn't want a relationship'

Justin, who quit Instagram over fan reactions to his romance with Sofia (daughter of crooner Lionel Richie), is said to have wanted something more casual.

Speaking to E! Online a source close to the chart-topper said: 'They were never officially together, but more casual hanging out and having fun.

'It was super hot and heavy, and because Justin doesn't want a relationship right now, he wanted to cool things down.'

However they were sure to add that 'It wasn't an intentional cool-off', but that 'it just sort of happened on its own'.

The couple's romance only managed to last a week, before TMZ broke the news that the relationship was not that serious to begin with. 

The split wasn't wholly unexpected, however, as the couple hadn't been photographed together since their Mexican getaway on August 29.

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.