The study makes a very incorrect assumption, which is that a person's report of their own tastes and habits will be more reliable than their partner's. Living in stable circumstances, settling into a mindless routine, a person's self-image diverges from reality. The person lives in the fantasy; the partner sees the reality.
For instance, even in just a four-year relationship, I ended up getting in arguments with my girlfriend about whether she liked eating Chinese food, watching new movies, going kayaking, or seeing a certain kind of music. I'd say she didn't. She'd disagree, saying, "Of course I like that, I've always liked that," and I'd counter, "It's been two years since we last did it and a year since I gave up suggesting it."
I would say in that case that I knew my partner, and she was ignorant of herself.
For instance, even in just a four-year relationship, I ended up getting in arguments with my girlfriend about whether she liked eating Chinese food, watching new movies, going kayaking, or seeing a certain kind of music. I'd say she didn't. She'd disagree, saying, "Of course I like that, I've always liked that," and I'd counter, "It's been two years since we last did it and a year since I gave up suggesting it."
I would say in that case that I knew my partner, and she was ignorant of herself.