Cats aren't social animals the way dogs are. They don't feel obliged to you or anything like that because they are not pack animals unlike dogs who see you - the owner as the pack leader and provider of food. A cat is only with you because it suits it.

My grandma who lived in the countryside had a cat. The thing would eat in the morning, then go away and wander the village and its surroundings for an undetermined amount of time. Sometimes it wouldn't come back for days. One day the cat went on it's way and didn't come back. It's possible it died somewhere, but I like to think that it just found a new home and stayed there. I've seen it happen.