The relationship — which has been public for only a month or so, though the pair were spotted flirting backstage at "The X Factor" in mid-November — came to an end last week with Swift, 23, flying home alone only three days into their vacation in the British Virgin Islands. The two reportedly met in March at the Kids' Choice Awards.
"They were on holiday and had an almighty row," a source told the Daily Mail, confirming they'd split up. "They are two young stars at the top of their game so who knows what will happen in the future."
Styles, 18, decided to hang around the BVI neighborhood, however, hopping over to Richard Branson's private Necker Island for a short visit, during which he was photographed hanging out in the hot tub.
In the wee morning hours he returned to Virgin Gorda, where he and Swift had headed after ringing in the new year with a public kiss at midnight in New York's Times Square. He flew home to London three days after Swift jetted off alone to the U.S.
So much for high hopes raised by that maybe-double-datey, late-December ski trip to Park City, Utah, where Selena Gomez and Justin Bieber also enjoyed the snow. (Though that's another couple reported to again be on the skids, if not over entirely after a big fight in Mexico.)
Swift was previously dating another youngster, Conor Kennedy, who's one of those Kennedys. They broke up in September.