They've been inseparable besties for five years, with Jordyn Woods even living with Kylie Jenner in the make-up millionaire's luxury mansion.
But now it has been claimed that Jordyn has hooked up with the reality star's big sister Khloe Kardashian's baby daddy, Tristan Thompson.
It's unclear what this will mean for the young women's intense friendship, with the Kardashian-Jenners previously closing ranks when they feel one of their number has been wronged.
So what will happen to Kylie Jenner and Jordyn Woods' friendship? Kylie is seen in a Snapchat posted on Monday, hours after Jordyn is alleged to have hooked up with Tristan Thompson
Having fun: But hours before this video was shot, Jordyn is alleged to have been 'making out' with her besties, sister's boyfriend
Controversial: NBA star Tristan and Jordyn, 21, were apparently seen kissing and making out during a house party on Sunday night, according to various gossip blogs
NBA star Tristan and Jordyn, 21, were apparently seen kissing and making out during a house party on Sunday night, according to various gossip blogs.
To add insult to injury, Tristan, 27, had apparently flown into Los Angeles specifically to spend Valentine's Day with Khloe, 34, and their daughter, True.
Just hours after to the alleged hook-up, Kylie and Jordyn were playfully Snapchatting from Kylie's mansion.
Both dressed in their pajamas, Kylie pulled faces as she lay under her quilt, before panning the camera to show her friend dancing in her open walk-in closet.
