If you can remember the good, you can remember the bad.....same brain memory works for both.
I remember both about my ex & yes, the negative out weighed the good especially toward the end. The bad started early on when I put my foot down, set boundaries but he constandly found new bad stuff to do & at the end of 33 years I had enough. I remember both about him but the bad is firmly planted in my mind exactly why I left. We all are quite capable of remembering both as long as we put them BOTH firmly in our mind