In In re Marriage of Dellitt, 213 Ill. App. 3d 155, 571 N.E.2d 523, 156 Ill. Dec. 739 (Ill. App. 3d 1991), the parties executed a separation agreement which provided for monthly maintenance of the wife until her death or remarriage. The separation agreement was not incorporated into the judgment of dissolution of marriage. Dellitt, 571 N.E.2d at 524. The husband petitioned the court to reduce his monthly payments based on a change of circumstances. The Illinois Court held that the case involved "contract law . . . and the terms of the settlement agreement entered into by the parties may not be modified except by the agreement of both parties." Dellitt, 571 N.E.2d at 525.