I am looking for a word which can be used to describe the situation where someone has previously done good deeds towards another and then subsequently wrongs them in some way. This is NOT betrayal.
The best way to clarify the situation I mean is to constrast it with it's opposite, which I would call "redemption", i.e. the scenario where someone has previously wronged another and then does something to make up for it.
An example to clarify; if John beats up Bob, and then subsequently saves Bob from getting run over by a car, we would say that John has redeemed himself, that this was an act of redemption. If, in an alternative universe, John saves Bob from getting run over by a car, and then at some point down the line beats him up, we recognize that John has negated his good deed and Bob is no longer in his debt. What is the word that best describes this act?
The best I can come up with is some form of the phrase "negated goodwill", but I was hoping to find a single word that would fit this meaning. Edit: A better phrase would be good too.