Taylor Swift is allegedly upset that American television personality/model Kendall Jenner and One Direction star Harry Styles have reunited. The two sparked romance reports after they were spotted getting intimate on a yacht at St Barts.

"Taylor heard from a mutual friend that Harry and Kendall are back together and she is completely shocked. She can't believe that Kendall would actually date Harry, especially after their last conversation when she said she would never, ever get involved with him again," a source told Hollywood Life.

"Taylor and Kendall actually bonded over dissing Harry and comparing notes on him. The fact that Harry and Kendall are celebrating New Year's Eve together is beyond weird to Taylor. She really can't trust anything that Kendall tells her, not now that she's back with Harry," the insider added.

It was previously revealed that the Red singer was single for a long time since splitting up with Styles. Swift, who has a history of dating high-profile celebrities including Jake Gyllenhaal, Joe Jonas, Taylor Lautner, John Mayer, Zac Efron and Conor Kennedy, split with Styles in January 2014, after dating for two months.

Meanwhile, Styles had addressed speculation if One Direction's latest song was influenced by his past relationship with Swift. The British boy band released their fifth album, Made In The AM, and it is their first without former member Zayn Malik, who left the band in March 2015.

The single Perfect was penned by Styles and Louis Tomlinson. The lyrics read: "If you're looking for someone to write your breakup songs about, baby, I'm perfect."

When Entertainment Tonight's Samantha Harris asked the 21-year-old singer whether he was referring to the Bad Blood hitmaker, Styles replied: "Obviously, you write a lot of stuff from personal experience, but it doesn't necessarily have to be so literal. People can interpret a lot of different things in different ways. And I'm not going to tell someone it's not about what they think it's about, because I think the whole point is - it's about whatever it means to you."