This may appear as a sync row error on updating a spouse relationship:
The statement has been terminated. The UPDATE statement conflicted with the CHECK constraint "CK_RELATIONSHIP_OWNER_VALIDSPOUSE". The conflict occurred in database "23695P_cd4d1fc9-53ab-499b-aefa-3035f9e418f8", table "dbo.RELATIONSHIP".
This error occurs when the relationship is on a Name_ID 0 record in TA. A spouse relationship (HUS/WIFE) cannot be with a group or organization record (Name_ID 0) in CRM. The solution is to move the relationship from the Name_ID 0 record to one of the names on the account, or to delete the relationship.