The rumour mill went into overdrive when X Factor host Mario Lopez revealed he saw them holding hands backstage at the U.S. X Factor last month.
And on Sunday, photographic evidence of Taylor Swift and Harry Styles out together for the first time only served to fuel the rumours of a romance.
They showed the pop stars enjoying a romantic stroll through New York's Central park, hugging a friend's baby and generally playing the part of a happy couple.
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Harry wore his trademark beanie over a shirt and jacket, while Taylor sported a burgundy coat over a beige sweatshirt and slim fitting jeans.
The twosome played with a friend's baby and sat on some steps for a rest at one point.
But some reports out on Sunday have shed doubt on the 'romance', with HollywoodLife.com reporting Taylor is allegedly not denying reports of their relationship 'to make her ex-boyfriend Conor Kennedy jealous.'
A source told gossip website 'She isn't denying in any way the reports of the people talking about her having a relationship with Harry because she wants to make Conor jealous.'
'And the way she thinks she is making him jealous is to show him that she has options, but in reality, she actually wants Conor and is just doing this to "Wear the pants in the situation." She has no interest in making the Harry thing work.'
The romance rumours were initially fuelled by eyewitness who saw the pair hanging out at backstage at the U.S. X Factor.
The show's co-host Mario Lopez also confirmed he saw the pair 'walking hand-in-hand', which no doubt will breaks hearts amongst many of Harry's teenage followers.
Mario told listeners of his 104.3 MY FM radio show: 'Taylor Swift was the special guest performer, and [here's] a little inside scoop for you.
'During rehearsals, Harry from One Direction came and slapped me on the back, and said, "Hey, Mario, how ya doing?" And I said, "What are you doing here?" And he sort of [pointed] toward Taylor.'
VIDEO: EXCLUSIVE video. Harry and Taylor's cute day out
Mario said he later saw them 'walking off hand in hand. So Taylor Swift and Harry from One Direction - you heard it here first. [They're] officially hanging out, I can say that much.'
Adding even more fuel to the 'are they, aren't they' confusion, the One Direction heartthrob reportedly picked up the blonde star, threw her over his shoulder and took her backstage following her rehearsal on the talent show while her mother looked on.
The two pop stars were both scheduled to appear on the show and had run into each other backstage during rehearsals which turned into a 'flirt fest', according to sources.
The official US X Factor Twitter page picked up on the romantic vibe, tweeting: 'Together in the lunch line (Cheeseburgers) laughing & smiling was @Harry_Styles & @taylorswift13! :) #internationalpoproyalty.'
Another eyewitness said: 'After she finished, he went up to the stage. They were joking and laughing. He picked her up and threw her over his shoulder and carried her off.'
The pair were said to have dated earlier in the year, before Taylor hooked up with Conor Kennedy.
According to RadarOnline, Harry and Taylor couldn't make it work out then as the blonde starlet was left 'heartbroken' after pictures emerged of the heartthrob locking lips with another mystery girl.