Some cats can and do get stressed when being left alone and other cats prefer being left alone without being stressed.
If your cat is stressed when being left alone the cat may meow excessively, or urinate outside the litter box or not eat as much or at all while you're gone.
If a cat is alone by itself and stressed it may be a good idea to get your cat another feline companion to keep them occupied and keep them from being lonely while you're away.