Hi Scully. Your problem is absolutely fixable. Go to the Living Room section of the Store and purchase the Usable Couch. It's listed between the bluish Used Couch and the Second Hand Loveseat.

Drag the Usable Couch down from the Decorate Tray and place it in your house. The tutorial should acknowledge it and stop asking you to place it. Please let me know if this resolves the issue for you.