"We were never boyfriend and girlfriend," she told Reveal magazine. "I think that's the first time I've ever admitted to what it was, because I've always just shrugged it off before.
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"But I think it's best to clear it up. So yeah, we had a short-lived thing that was just a bit of fun. Then we went off in our opposite directions.
"Harry and I had a laugh," she added. "It was brief, but fun, and then we moved on. We haven't spoken in a while – he's one of the most famous people in the world now."
The pair were first linked back in 2012 after they were spotted spending time together in London.
Just before, Emily had tweeted about being a fan of the X Factor contestant.
"Does Harry from One Direction HAVE to be 16?!" she wrote. "Let's pretend he's 18 at least! Then there would only be One Direction he would be going… to the bedroom!"
Harry has dated several high-profile women since he shot to fame in 2010's X Factor.
The then-18-year-old sparked controversy in 2011 when he began dating Xtra Factor presenter Caroline Flack, then 32.
The pair split after a few months in January 2012, and shortly after he began a relationship with model Cara Delevingne.
The couple parted ways and he soon began seeing popstar Taylor Swift.
Their relationship was said to have ended acrimoniously in late December 2012. A source told Vanity Fair, "Harry was all, like, 'You're amazing – I want to be with you, I want to do this.'
"But soon enough, she couldn't handle his constant partying, and couldn't trust him. He disappeared one night and after that it was like he just didn't want to keep going."