I do understand
This one's just a cat. I pet her and she purrs, but she doesn't sit on my lap and she has no personality. Molly played fetch with scrunched up paper balls. She was mean. She was indifferent. But she was Molly.
I have always gotten a new dog after the old dog died, but it seems to be different with dogs. You learn to love them in a different way from the old dog. They worm their way into your heart just by being themselves.