Resentment is usually a feeling which has little to do with ethics.
Actions are more easily analyzed for ethical value.
I guess that you’re considering the action of showing resentment by being absent or cold to them.
From a utilitarian perspective this could serve the purpose of communicating your resentment indirectly which may increase the overall good by preventing this scizsm from infiltrating other parts of your life and others. On the other hand this outcome is not guaranteed.
If you apply value ethics of your actions it really depends on what ideals you hold yourself to.
If you take a completely honest person as your ideal, direct communication is probably more ethical than indirect communication, but indirect communication would still be superior to deceiving them into thinking you agree with them in any way.
Instead, you may idealize an honest pacifist who would value indirect communication higher than direct if direct would also come with conflict.
These are my thoughts, I am by no means an expert in ethics.












🤣 beware the Linux users