Having personally taken a medicine on a daily basis, that is known to affect cognition in terms of memory, and especially its short-term aspect, I got to realise, that much of how I had treated people in the past, had been coloured by memories of the less significant events; those that lingered.
Because my recording of such memories became a lot less effective, after many years of taking those tablets, I would need to consciously try to retain them, or they'd be likely to go. Subconsciously, and very importantly, I began assuming that others are that way too, and it became a useful societal model.
We will always remember the most shocking, painful, and otherwise significant events that we experience, but I learned that life would go on happily, whether we very actively ignore the pettier stuff, and assume others did the same, or that our poor mental cognition does it for us, consequently influencing our behaviours.
What does it matter what the root of our actions are, when others see us in the same positive way regardless? It's another life choice, perhaps linked to Christian forgiveness, but more tangible.