The transition of "knowing"

Everyone experiences the transition of "knowing" with someone else at some point in life. It is that period, that moment of transition that occurs between knowing and not knowing a person. You can know a person for example, casually like an acquaintance, but at some decisive moment, a change occurs. Generally, both parties feel this change innately, a definite shift. The threshold crossed is an almost imperceptible barrier, but a barrier nonetheless, and when it is crossed, there is no returning to the land of "not knowing"--it's all knowing from thence on out--and once knowing and being known, who would want to return to that land of "not knowing?" I honestly don't know...