Kardashian sisters warn Kendall against Harry

"The Keeping Up with the Karadshians" stars Kim, Khloe and Kourtney Kardashian have reportedly warned their stepsister Kendall Jenner not to fall for singer Harry Styles.

The reality TV stars have asked Kendall not to get too involved with the One Direction singer, who has been romantically linked with a string of women, including clebrities Taylor Swift, Cara Delevingne and Natalie Imbruglia, reports contactmusic.com.

However, the 18-year-old has reportedly told her sisters that it is too late for their intervention.

"Kim, Kourtney and Khloe are super worried about baby sis, and keep warning her, 'Don't fall in love with Harry, he's going to break your heart'. But it's too late, Kendall told them, 'I'm already madly in love with Harry'," said a source.

Kendall, 18, and Harry, 19, met in November and have since been on romantic dates in New York and London, as well as a ski trip in California.

While the Kardashian sisters are worried for their younger sister, their mother, Kris Jenner, has no problem with the romance.