Garage Cat Sam (He was big on Mopars - Darts in particular.)
I got two cats right now that I've taken in...some asshole abandoned them. They're sisters. An Orange and Peach cat. They get upset when the other is gone for awhile.
Peach cat has cancer. We were about to put her down a few months ago, but I increased her food and she rebounded quite a bit. She still likes to eat but it can't get through to the other end very well. I'm dreading that day and I feel your pain, OP.
I don't know how to tell the orange cat what happened when her sister is gone...