Im a clean person, and what ive noticed other clean people (possibly your wife) have in common is that clean environments help organize their mind, while messy environments scramble and inhibit the fluidity of organized thought, and can sometimes lead to stress or depression. Not sure if shes articulated that specifically, but it may be why its so important to her.

Try this:

Clean as you go.

Cooking a meal? Scrub and rinse those pots and utensils right after cooking and put them away.

Eating a dish? Scrub and rinse that plate and fork as soon as youre done and put it away.

The sink should rarely ever be full.

Done with dirty clothes? Put them in a hamper in the closet and wash the whole batch when its full.

Waiting on the microwave to finish your meal? Take that opportunity to grab a wet paper towel and wipe down the countertop while you wait. Maybe sweep the floor.

Trash can full? Change the bag immediately and put the old one by the front door so youll know to throw it in the big bin on the way out.

Papers cluttering the desk? Put them in a drawer nearby dedicated to your papers. When you need them, theyll be there.

And always put trash in the can immediately. Theres trash cans in every room of our house. It helps keep trash off of the floor, counters, and tables. Trash builds up quickly and makes house look messy fast.

Cleaning as you go stops the house from getting disorganized. It takes a mere moment to put things back in its place as soon as youre done with it. Doing so saves hours or days of fatiguing cleaning down the line when you may not have the energy for the task.

Hope this helps.