One Direction star Harry Styles and his rumoured girlfriend, American television reality star Kendall Jenner, have reportedly ended their relationship after three months.

Styles and the 18-year-old Keeping Up With the Kardashians star split due to hectic work schedule.

"Kendall has been focusing on her modelIing and Harry is preparing for work on the band's fourth album, as well as their stadium tour," a source told the Sun.

"The reality is that with everything they both have going on, it's impossible to sustain anything serious. There's been no major fallout. They're definitely still friends and haven't ruled anything out in the future," the source added.

Styles was first linked to Jenner in November when they were spotted leaving a dinner date at Craig's restaurant in West Hollywood.

The two dismissed the speculation that they were dating, with Styles announcing on ABC's Good Morning America that he was single.

According to Daily Star, the two also avoided each other while Jenner was in London for Fashion Week.

"Harry purposely didn't go to the Topshop show or have his planned party at The Box so people wouldn't speculate about him and Kendall," an insider told the website.

"There were plenty of opportunities for them to meet up but Harry went to the FA Cup game between Arsenal and Liverpool instead of seeing her. They got on but there wasn't enough spark to keep it going, especially as Harry is about to go on tour for six months. They would never have any time to see each other," the source said.