Taylor Swift is reportedly "furious" Kendall Jenner is dating her ex-boyfriend Harry Styles.
The 'Shake it Off' hitmaker, 26 - who romanced the One Direction hunk for three months in 2012 - is said to be really annoyed the gorgeous model, 20, is rekindling her relationship with the handsome singer, 21.
A source explained: "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.
"Taylor and Kendall actually bonded over dissing Harry and comparing notes on him."
Kendall and Harry - who first dated in early 2013 - sparked rumours they were back together earlier this week when they were spotted sharing a smooch on a luxurious boat in the Caribbean island of Anguilla on New Year's Eve.
The insider added to the HollywoodLife.com: "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!"
However, despite feeling "betrayed" by her pal, Taylor doesn't seem to be jealous of their blossoming relationship, as she's loved up with her boyfriend Calvin Harris, 31.