There are those who dwell on the bad on the hurt on the pain. I don't know what they gain from doing that but I think you're right. Memory seems to dim negativity. Thank you for your reply m2c! :)
Memories are funny things. Many of the memories we have didn't actually happen as we remember them.
We can’t possibly remember every tiny detail we see (let alone over a lifetime), but our memories would feel incomplete if there were big swaths of gray running through them. So our brain fills in the details as best it can, borrowing from other memories and the imagination in order to build what feels like a complete picture. We lose the details of experience rapidly but retain our understanding of its gist much longer. For example, after attending a baseball game, we may quickly forget what the score was, who pitched, and what we had to eat, but not that our team won and we had a fun evening.