Is it possible to redeem a character who is supposed to be good, but does something inexplicably bad?
Let me give you an example so you can further understand where I'm coming from.
A and B were exes. In a night of high tension and emotions, they end up sleeping together. It's later revealed that B had a girlfriend they hadn't brought up for numerous reasons. However, the character isn't supposed to be a bad person.
Is it possible for a character to be considered "good" in the eyes of the readers after doing something so universally deemed as morally bankrupt? How much should the character do to come back from something like this? Or is it possible that no matter what, this will stain the character's reputation?