Your wife is right, there's nothing wrong with grains per se or that other starchy food paleo gurus like to demonise, potatoes. It's the way they're prepared and used as vehicle for the consumption of fats that's the problem. Think about it; there are plenty of fatties who attribute their weight problems to "carbs" like pizza, potato chips, doughnuts and cookies, all high fat foods, but have you ever heard of anyone getting fat eating brown rice, pasta, or plain old boiled potatoes?
My advice; ignore this low-carb fad diet nonsense and go ahead and eat all the brown rice, oatmeal, pasta, baked/boiled potatoes, fruit and veggies you want. Just don't cook them in excessive amounts of oil, add fats to them at the table, or eat them with high fat foods and you'll be fine.