Let 2 people swap their view points with each other. It's like swapping eyes - you see from the other person's view point and vice versa.
This doesn't apply to anything other than sight: you still hear, feel, and live as "you".
This can be achieved with special helmets with a camera and some kind of "vr goggles" maybe?
Now let them live like this for a week, 0 breaks, 168 hours.
Living like this becomes very very hard provided that you're not constantly next to the other person all the time.
But what happens when they're not next to each other?
..?
Profit.