Are your internal and external relationship scores different?

My wife rates our marriage a 7. A SEVEN! I dont know how. I rate it a 4. We are mostly sexless, have no common hobbies or interests, dont talk much, she doesnt cook or clean and neither do i. I drive a shit car, we live in a shit house. She has a nicer car. My son has a nicer car. He still lives at home (which i like). I think people on the outside looking in must wonder how we are still together.