You do not need to allege nor prove fault for a divorce in Arizona. This is a "no fault" state and one need only establish that the marriage is "irretrievably broken," meaning that there is no reasonable chance that the spouses want to keep the marriage together and the marriage is "dissolved" after a waiting period of at least 60 days post service of the papers. This is true unless you have a "covenant marriage," then there are grounds that must be alleged and proven.
Daniel earlier answer is correct. Well over 90% of marriages are non-covenant marriages here in AZ. I'd say over 99% probably. In order to divorce a covenant marriage, you either need cause, a long-term separation, or both parties need to agree to divorce. Most family law attorneys have never done a covenant divorce. I, however, actually have had ONE covenant divorce.
For the non-covenant divorces, no cause is required and only one party of the two needs to want the divorce. If the other party does not want the divorce they can request conciliation counseling and a stay to the proceedings but, in my experience, half of those that go into conciliation counseling still proceed to divorce.
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