This is one of the reasons why I try to avoid having pets. Dogs and cats have much shorter lives than us, so the eventual heartbreak when they pass is difficult. They bring so much love, joy, and companionship, and they only want a little bit of our time and attention in return. For a lot of people, their pets are their first child/baby. Some even use it as preparation for when they have a kid. From what you've said, I think Buster had a wonderful life, and I know you will continue to treasure him.