It's not so much the things we don't know about relationships that can hurt us but rather the things we THINK WE KNOW. Myths from "they lived happily ever after" and "love means never having to say you're sorry" to "once a cheater, always a cheater", permeate our culture and take root in our minds, preventing many couples from doing the work required to build a good, lasting relationship.
Myths can destroy relationships and are harmful to long-term success. Not only that, they have little substantive foundation beyond a willingness on the part of the general population to accept them as factually true.
Learning to recognize and free yourself from the limits of these beliefs, and others, allows you to find new ways to strengthen and heal your relationships so you can move toward the kind of love you thought only occurred in myths!