Anger, frustration and deep-seated resentment are all sypmtoms of liver imbalance.
The liver is responsible for the smooth flow of qi; when it becomes stagnated, it also stagnates our emotions. Anger and frustration tend to get stronger during moments of higher stress and overwhelm. When in balance, these emotions are a healthy part of our day to day experience. However, if these emotions are not expressed or not released - communication, music, exercise, journaling, creative outlets, etc - they stay stuck in our body. Long term they start to become feelings that are much harder to shift: deep seated resentment.
If you are experiencing an excess of these emotions, consider booking a Traditional Chinese Medicine Consultation to help get to the root of the issue.