Our brains are wired to be negative.
Nothing has gone wrong. They are working the way they are suppose to.
Our brains are simply wired to be looking for potential problems. It's sensitive to seeking out and avoiding potential pain.
It's why everyone gives more attention to bad news than good. Why you're harping on the one critiquing comment about your last presentation than the five positive ones you poopoo on.
We're wired to feel more the sting pain over the surge of joy.
Not only does it make us more likely to remember negative events, but more likely to dwell on them. Replaying it over and over sends us though it over and over. Which intensifies them. You only technically HAD to experience the thing once. Mentally dwelling sends you through the thing 996 more times, even though it's long over.
Evolutionarily speaking it's more important to remember the thing that hurt, so we can avoid it, than it is to remember...