These words are usually said in anger and frustration. The speaker is unilaterally ending the conversation, effectively saying that the other person has lost their attention and don’t have permission to speak anymore. The speaker is essentially declaring that they just don’t want to work it through, that they don’t care about the relationship (at least at the time).

Even if the disagreement is going round in circles, shutting down the conversation should be a mutual decision. “I think we are both tired and we aren’t moving forward in this discussion. Should we put it aside for now and pick it up tomorrow?”