The phrase "came to an agreement" implies the resolution of a dispute or the achievement of a mutually acceptable understanding. Antonyms for this phrase could include words such as disagreed, disputed, argued, or conflicted. Other antonyms might include words such as diverged or deviated, suggesting that the parties involved failed to reach a common ground. The phrase "failed to reach an agreement" would also serve as an antonym, indicating that negotiations broke down or were unsuccessful. Whatever the antonym used, it would suggest that the process of reaching an agreement was not successful, and the parties involved were unable to find a satisfactory solution to their issues.