Your wife says something. The body has a reaction. Hurt. Defensive. Surprised. You watch yourself react. What you're watching isn't a fact about her. It's a fact about you. The same comment from a stranger wouldn't land the same way. The comment landed where it did because of the version of you that lives in this marriage. The conversation didn't just reveal her. It revealed you to yourself.
K's most-used line about relationship: relationship is a mirror. You don't see the other person. You see what you have become around them. The reactions, the buttons, the patterns, the way the body responds — all of it is information about you, not about them. The mirror was always there. Most people just look at the surface and assume they're seeing the other person.
The standard view treats relationship as a transaction between two stable individuals. K's view treats relationship as the place where individuals reveal themselves as the conditioned, reactive, fragmented creatures they are. The closer the relationship, the higher the resolution of the revealing. A casual acquaintance shows you very little. A spouse shows you almost everything, if you can stand to look.
Most people can't stand to look. The reactions get blamed on the partner. You made me feel that way. The mirror gets accused of producing the image it's reflecting. The marriage runs on this misattribution for decades. The mirror is just doing what mirrors do. The image is yours.
Relationship is the most accurate self-portrait you have access to. Other people are the medium that makes the portrait visible. Read what shows up in the mirror as information about you, not as information about them. The marriage is the developing tray. The image being developed is yours.