Well, the good news is, you did nothing wrong. Cats are creatures of habit, and they HATE changes. Talking from experience, yes, I too have a "pee-boy" and over the past 2 years have been redecorating my house, with his help Some cats are just more stressed when things change. I have found that the Feliway plug-ins work well, but if you know you are going to do things (paint, carpet, etc) plug it in a week before you start. Also give lots of attention to the culprit, they are stressing now and need comfort. Another thing my Vet recommended, take something with their scent on it, their blanket, bed, etc, and rub it all over the new thing. That way there scent is already there and it should cut down on the need to "mark" it. Oh, and unfortunetly, this will occur again sorry......