American singer/songwriter Taylor Swift is reportedly still upset with American television personality/model Kendall Jenner for dating One Direction star Harry Styles.

According to a report in Hollywood Life, the 25-year-old Shake It Off singer feels the 19-year-old Keeping Up With the Kardashians star "backstabbed" her by doing so.

This comes after reports emerged that Kim Kardashian's half sister thinks the Red singer is a "mean girl".

"Taylor has no idea why Kendall would think she is a mean girl. If anything, Taylor thinks Kendall needs a serious lesson or two in the girl code department. For starters, don't date your friends' exes! Taylor has little patience for people who don't respect the meaning of friendship. She feels like if Kendall really valued their friendship, she would have never stabbed her in the back by dating Harry. It was a real low blow and till this day, Kendall has never apologized," a source told the website.

It was previously revealed that Swift was single for a long time since splitting up with the 21-year-old boy band singer.

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 last January, after dating for two months.

Meanwhile, Styles was first linked to Jenner last year in November when they were spotted leaving a dinner date at Craig's restaurant in West Hollywood. However, they split after dating for three months.