"Knowing Thyself" should be the hallmark of any person, and more importantly, when in a relationship.
Indeed, understanding what our own emotions tell us and knowing how to attend to our needs is, not only necessary, but also a very good idea that lifts the pressure from other people's shoulders.
Many arguments start with "he/ she does not understand me". Well, maybe this is simply because it is too much to ask sometimes. An adult's life should not be centered on guessing, or second guessing our needs. If we love a person, we should wish for him/her to thrive, grow, expand and be happy. Allowing each partner in a couple to focus on his/ her own life, not only fosters the love each partner feels for each other, but also brings more to the relationship itself.
Therefore, the position by default of a person should be: "I know my emotions and what they mean. I also know what to do with this knowledge, how to act, and express myself softly and respectfully with others, after I have understood myself. This implies responsibility, self-respect, sufficient alone time, observation, meditation and empowerment!