When it comes to disagreements, it's helpful to have a range of antonyms for the phrase "fail to agree about." Some good options include "concur," "harmonize," "unite," "accord," and "agree." By using these words, you can convey a sense of cooperation and mutual understanding that is often lacking in disputes. Other antonyms to consider might include "compromise," "negotiate," "settle," and "resolve." Whatever words you choose, the key is to create an atmosphere of productive dialogue and compromise, where all parties feel heard and taken seriously. With the right language and approach, almost any disagreement can be resolved and harmony restored.