The man changed the cat when his wife was on a business trip and still she did not notice it. But once the man decided to tell the truth and explained why he did so.
The cat was very aggressive.
And when his wife was on a business trip he decided to change the cat.
But he did not reveal it to anyone.
He looked for cats and found the same cat. This cat was more friendly and calm.
And the man took the original cat to another shelter.
Many years have passed and his wife did not feel the difference. But she was happy as the cat behaved calmly.
No one knows how the fate of the original pet has been. But he behaved calmer in the shelter than at home.