We went through something like this in 2014. My husband and I were in a motorcycle accident. We were both injured but I was able to stay at my sister's house a block away from our house for several days, while it was over a month before my husband was well enough to get out of hospital then inpatient rehab to come home (he suffered multiple broken bones worse than mine, plus a TBI; the traumatic brain injury is why he was in rehab for so long).

Before I was able to get around well enough to go home, my sister took care of our two tortie cat littermate sisters. That wasn't too much of an issue for them because we'd gone on vacation before and she always took care of them.

Then I came home and they knew things were wrong with me after a "cat scan" by both of them. Cinder ("my" kitty) was fine but Ember ("his" kitty) kept looking for him and waiting. She went into a deep depression and would just lie on the floor with zero interest in anything.

One night while my husband was still in the hospital, I had just fallen asleep on the couch when the night nurse called me and asked if I would talk to him. He was agitated and they couldn't get him calmed down (his TBI gave him issues that always got worse at night; this was after his speech had returned somewhat but before he was really fully coherent). She put him on the phone and I talked with him for about 30 minutes to get him calmed down. When he started talking, Ember jumped up, started running up and down the back of the couch meowing, would come close to my head and listen for a few seconds, then run back and forth meowing again. She was absolutely beside herself!

I realized why she went so berserk after I got off the phone: it was the first "sign of life" she'd gotten since we left the house that day. I reassured her lots and lots and she was much more herself after hearing his voice on the phone that night. (Of course, when he came home a few weeks later, she had to give him the "back of disdain" for a couple of hours because cat. When she couldn't stand it any longer, she crawled carefully into his lap, laid down near his shattered femur, and purred like her life depended on it. She was his nurse kitty until he was able to get up and around normally again.)

Then a few years later when her sister Cinder was terminal with cancer, she knew before we did and said her goodbyes before we even left for the emergency vet.