When you're rich and famous, it can't be easy to trust certain people when you don't know their motives.
Chrissy Teigen and John Legend, for instance, don't need Kim Kardashian and Kanye West to stay afloat, so Kim and Kanye never have to worry that Chrissy and John befriended them for the wrong reasons and the couples' bond is stronger than any silly misunderstanding. Last year Kanye didn't mind when John reached out to disagree with him on an issue, while John was secure enough in his own convictions not to have hard feelings when Kanye posted their private text messages for the world to see on Twitter.
Water under the bridge, Kim and Kanye attended a baby shower for Chrissy and John's second child just a couple nights later, no hard feelings.
When it comes to befriending celebrities, people tend to show their stripes fairly early on. Then, either they're never to be heard from again, or they pass all the tests and maybe even become trusted friends.
Understandably, a personal betrayal coming from one of those trusted friends would end up being very hard to stomach.