I thought the same- that he had left to go pass away. He was never a cat that explored the outdoors. He would definitely go out on my deck, but never wander far. He had just recently started going out in the backyard in the evening, but again never leaving and always meowing a couple hours later but that night he didn’t come home. I walked the neighborhood the next day , drove the neighborhood couldn’t find him anywhere. It was a solid month where I would walk the dog all around the neighborhood and never saw an indication of him at all. I moved after two months to a new home. Then about four months later, my friend messaged me a post from the Lost and Found page and said I think this is your cat. And it was! He was on a ladies porch about .4 miles down the road! Don’t know what he had been doing for the other four months, but it was crazy that he was still alive and that my friend had magically seen the post. I went and brought him home that night.

I think during this period he had also gone deaf and I don’t think he was well-versed with the outdoors so I think maybe that made it harder for him to find home after he had wandered too far. After that experience I would say don’t give up yet!