"It's okay Sandy, he didn't die or anything."
But it is death, isn't it? It's the death of a friendship beyond comprehension, where both participants gave so much of themselves, and then it was brutally and tragically cut short. There's really nothing else to compare it to, other than death. The separation is the same.
Even if (when) Michael and Kendall reforge their relationship, it won't be the same one it was before. It will be a new life form, like the friendship between Kendall and Chet. Thankfully, even as things die, new life always seems to find a way.