Model Kendall Jenner. (Pic: Instagram)

Kendall Jenner doesn't know if her relationship with Ben Simmons will be "long term".

The 23-year-old model has been dating the basketball player for several months but she admitted one of the reasons why she doesn't like to talk about their romance is because nothing is "super-certain".

She said: "I'm very young and right now I feel like relationships aren't always super-certain and I don't want to bring too much attention to something if you don't really know long term [what it's going to be]."

And the 'Keeping Up With the Kardashians' star worries things will get "messy" if she brings the spotlight to her romance, especially having seen her sisters' relationships playing out in the public eye.

She told Australia's Vogue magazine: "I got a glimpse of how my sisters dealt with [the attention] and it's cool to learn from that. 

"For me, a lot of things are very special and very sacred, like my friends and relationships, and I personally think that bringing things into the public makes everything so much messier...

"A relationship is only meant to be between two people, and the second you make it the world's business is when it starts messing with the two people mentally. 

"Like once everyone is let in, you're letting all these opinions into your relationships, and I don't think that's fair."

Despite her comments, Kendall is open to the idea of getting married to Ben, also 23, but not in the near future.

Asked if she's planning to get engaged, she laughed: "Maybe. Definitely not now, but maybe one day." 

When she does get engaged, the brunette beauty previously admitted she'd like her partner to choose the ring.

She said: "I mean, I kind of love the idea of letting the man pick it and having it be that pretty thing that he kind of thought of himself. 

"And having the feeling of like, oh, he made this with me in thought, kind of a thing. I like thinking that just the way it was made reminded him of me. That to me is kind of romantic. 

"But at the same time, I'm the type of person that would give hints, and be like, 'I kind of want this.'