Illness
One day, the kitten got ill. Immediately, the couple took it to the vet; there, they were told that it seemed like the cat had been poisoned by something he had eaten, probably some venomous mushrooms.
It seemed to be too late to do anything about it. The cat passed away right there. Then, when the couple got back home, immersed in their grief, they noticed something: the crow had been waiting for hours outside like it could feel something was wrong. It saw the couple carrying the body and let out a sad squeak.