It's tempting when you both work from home to spend all day in your pajamas or sweatpants. Yes, this is comfortable. But resist the urge. Wear day-time clothes during day-time hours. This means, at a minimum, jeans or shorts.
If you don't have to commute to an office, you don't have to wear a suit. But wearing sweatpants or pajamas every day shows your spouse that you don't care enough about his or her opinion to make an effort. Ditch the sweatpants once the working day begins.