The One Direction heartthrob, who was previously romantically linked to pop beauty in December 2015, has poured cold water on rumours he's dating the 24-year-old singer after they reunited at the American Music Awards last month, and while he insists he's single, he showed interest in the brunette beauty.
Asked if they have struck up a romance and if he is dating anyone, Niall told Ryan Seacrest on his radio show 'On Air With Ryan Seacrest': ''I don't have a girlfriend.''
And when it was suggested he should date the 'Hands to Myself' hitmaker - who previously dated Justin Bieber - the 23-year-old star said: ''Sort it out!''
Meanwhile, the 'This Town' hitmaker reiterated that One Direction will return one day and that nothing has changed between them.
He said: ''It's pretty much in the same position as it was when we told people we were taking the break. We're just sort of chilling out ...
''We took the break at a time when we thought it was right. We finished five years of solid touring for nine months of the year.''
The foursome - Niall, Harry Styles, Louis Tomlinson and Liam Payne - keep in regular contact via email.
He added: ''Everyone's been great. We all email and stuff like that, and everyone keeps in touch ... I see Louis [Tomlinson] quite a bit, we don't live too far away from each other. I haven't seen Harry [Styles] in a while, and I haven't seen Liam [Payne] in a bit either.''
And, it's not the first time Niall has revealed his feelings for an ex, as he recently admitted he still has a crush on ex-girlfriend Ellie Goulding.
During a round of 'Who'd You Rather' on 'The Ellen DeGeneres Show', Niall picked the 'Still Falling For You' hitmaker.
He gushed: ''It's official!''
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