Source: Bang Showbiz NewsRita Ora is thought to have ended her relationship with reality star Rob Kardashian due to their incompatible work schedules. The 'How We Do' singer called things off with the 'Keeping Up With The Kardashians' star due to her hectic work schedule and their incompatible jet-setting lifestyles, prompting Rob to unfollow Rita on twitter and delete all photos of her from his Instagram account. A source told The Sun newspaper: "It's really sad -- they really liked each other but with him living in LA and her over in London, it was becoming impossible to maintain a relationship."They'd only decided to go public with the romance a couple of months ago so as not to put any pressure on themselves but they've already split. Rob has now deleted everything on Twitter that reminds him of Rita."Rob was due to celebrate Rita's 22nd birthday at DSTRKT nightclub in London last week (26.11.12), but the pair allegedly ended their budding romance before the big event after a long discussion over the phone.While the reality star's family had welcomed Jay-Z's Roc Nation protege into their clan, his eldest sister Kim Kardashian never appeared to warm to the British star and caused controversy in August when she declared Rob needed to find an Armenian girlfriend instead.Kim tweeted: "When out to dinner w my brother @RobKardashian every gorgeous person Persian/Armenian girl stares at Rob! I think that's what he needs in his life!"