Emotions impact decision making. Normative decision making models struggle to internalize this impact. Resentment, grievance, and bitterness are similar to each other, but different enough for me to include them all. They are low grade long term emotions that seem dysfunctional for those who carry them, but maybe functional at some level to encourage us to treat others better.
According to Wikipedia resentment is a complex, multilayered emotion that has been described as a mixture of disappointment, disgust, anger, and fear. You can feel resentment directly toward a person or group for how they mistreated you or you can feel resentment toward a person or group because they have been treated better by others or seem better in some way than you. Grievance somehow seems more specific, while bitterness seems more general and resigned. Resentment is anger’s passive aggressive brother.
In 2022, resentment seems to be driving all sorts of decision making all over the world. Vladimir Putin declares war on Ukraine. Millions of people suddenly do not want to get vaccinated and millions of others believe an election was stolen without evidence.