The term “irreconcilable differences” (also known as irretrievable breakdown, among other synonyms) refers to conflicting viewpoints between a married couple on basic, fundamental issues that make the marriage unworkable.
In no-fault divorce jurisdictions, a couple can be granted a divorce on the grounds of irreconcilable differences. In such a case, there is no need for the couple to prove wrongdoing by either party in the breakdown of the marriage.
Most courts will never make any inquiries into whether an irremediable breakdown has actually occurred. Rather, as a practical matter, a court will generally always grant a divorce as long as one of the parties in the divorce states that the marriage has had an irremediable breakdown.
In states where divorcing parties must cite a reason for a divorce, irretrievable breakdown is a blanket term that covers any reason that results in either party being unwilling to continue with the marriage. Only one party must cite irretrievable breakdown for a divorce to be granted.
Prior to 1970, most states required proof of fault or wrongdoing by at least one individual in a marriage to grant a divorce. In 1969, California became the first state to enact a no-fault law; a couple didn't need to prove wrongdoing in order to be granted a divorce. The District of Columbia and all of the states in the United States eventually adopted no-fault divorce laws, which allow a divorce on the grounds of irreconcilable differences.
Often, people will file for divorce using irreconcilable differences even if there are other legal grounds for divorce (such as adultery). This is because divorces filed as irreconcilable differences often take less court time.