irreconcilable differences

Definition from Nolo’s Plain-English Law Dictionary

The most common basis for granting a no-fault divorce. As a practical matter, courts seldom, if ever, inquire into what the differences actually are, and routinely grant a divorce as long as the party seeking the divorce says the couple has irreconcilable differences. Compare: incompatibility, irremediable or irretrievable breakdown

Definition provided by Nolo’s Plain-English Law Dictionary.