Kendall Jenner has revealed her niece Stormi Webster has a crush her boyfriend

Appearing on 'The Tonight Show with Jimmy Fallon', she quipped: "[Devon and Stormi] have an amazing relationship. She has the biggest crush on him, and I'm jealous sometimes. I'm like, 'Stop — can you guys not?' "

Kendall, 25, and Devon, 24, officially started dating earlier this year, while Kendall also talked about how she strives to be a "cool"

aunt to her nieces and nephews.

She said: "I always wanna be like, the cool one and like, liked. There's

18 now going on 20 so I have a lot of them but it's fun. It's really fun."

The revelation comes very soon after Kendall's sister Kylie, 24, announced that she is pregnant for the second time.

The reality star announced the news in an Instagram video which showed daughter Stormi handing grandmother Kris Jenner, 65, an envelope containing containing baby scan photos.

Kendall also revealed how she heard the news in a similar way.

She said: "[Kylie] called me and I answered the phone and she just had a little picture of her sonogram and I was like 'Oh my God!'"

However, news of the pregnancy did not come as a surprise to Kendall, as she revealed she was pretty much expecting it.

She admitted: "I wasn't really shocked. I felt like it could happen some day soon but I was excited. I'm very excited".

Kendall's mother Kris is just as delighted about the baby news, as she revealed this week: "I'm really excited. Number eleven, it's really great!"