Any fool can know. The point is to understand.
In any real relationship there comes a point where the past raises its ugly head, and that’s where things get complicated. The problem is that if the ugly past is not accepted and understood, then the future is going nowhere except into a slow-motion train wreck.
What is needed is real acceptance and understanding of the simultaneous past / present / futures. For without that there is no point in continuing any relationship.
What is acceptance, and what is understanding? There is a big difference between reluctant acceptance ~ which is what most people descend to ~ and true honest understanding.
To reach the nirvana of true and honest understanding, there must first of all be true honesty. And, in this life true honesty is as rare and fleeting as a double rainbow.
I have never known real honesty in a relationship. Perhaps excepting now.