Like others have mentioned I would switch up on the who is feeding and walking the dog. If your dog sees your wife as the person who is providing food and treats and taking it for walks and training, the dog's attitude will change. It is no way acceptable to let this keep up though. If the dog gets serious, your wife could be bitten badly. A good trainer that will work with your wife and the dog together would be a good solution.
Snake Vom Eselspfad RN CGC (AKA Raina) 3/5/08
Pyrate CGC 4/1/03-5/16/12 RIP
Too many to list waiting at the bridge but remembering them all