I think it's important to have closure in any relationship that ends - from a romantic relationship to a friendship. You should always have a sense of clarity at the end and know why it began and why it ended. You need that in your life to move cleanly into your next phase.
Memories may escape the action of the will, may sleep a long time, but when stirred by the right influence, though that influence be light as a shadow, they flash into full stature and life with everything in place