It depends - mostly, I think, on whether that painful event was the only memory (or the most lasting impression) they had of that person. Someone who had a bad experience with a stranger would forget the person along with the event, but someone who had a bad experience with a family member or long-term friend would only forget the event but remember their other memories of the person.
[That's her best guess, based on her observations.]
no subject
[That's her best guess, based on her observations.]