You can't keep a cat under control all the time - they like to wander & be independent. That means that they're out in the dangerous wide world alone - but that's where they want to be. So sometimes they just don't come home. Its sad that the cat has gone - but its great that your wife gave him all that love and freedom for 14 years. Not knowing what happened to him is the hardest thing - but that is part & parcel of the freedom you gave him.