Keeping Up with the Kardashians star Kylie Jenner, 15, shared an intimate Happy Birthday post to her rumored boyfriend Jaden Smith on Instagram.

In it, she writes that he’s her “best friend” and understands her “like not many do.”

“Although we can't remember exactly when we met, I couldn't be more grateful that we did,” Jenner writes. “You understand me like not many do & you always know the right time to make me laugh. And no, you haven't failed once to catch me when I attempt to walk or open the door on my every entrance. Happy birthday to my best friend.”

Kylie’s famous mom, Kris Jenner, who is launching her own talk show on Monday, also wrote a sweet message to Jaden on her Instagram account. She posted a picture of the two together and wrote “Happy Birthday @iputthesocietyonmyback I love you Jaden!! Have the BEST day ever!! #bestkidever.”

Us Weekly reports that although the two are photographed together often, they haven’t admitted to dating yet. Jaden, the son of Will Smith and Jada Pinkett Smith, said in an interview with Wonderland Magazine in May, "She's one of my best friends. It’s pretty awesome."

Jaden shares a birthday with Kylie’s niece, Penelope Scotland Disick, who’s mom, Kourtney Kardashian wished a Happy Birthday to on Twitter, writing “Happy 1st birthday to my sweet precious angel. I can not believe it has been a year. Truly blessed.”

image: Instagram