Grounds for Divorce in Illinois:

1. Without cause or provocation by the petitioner: the respondent was at the time of such marriage, and continues to be naturally impotent; the respondent had a wife or husband living at the time of the marriage; the respondent had committed adultery subsequent to the marriage; the respondent has wilfully deserted or absented himself or herself from the petitioner for the space of 1 year, including any period during which litigation may have pended between the spouses for dissolution of marriage or legal separation; the respondent has been guilty of habitual drunkenness for the space of 2 years; the respondent has been guilty of gross and confirmed habits caused by the excessive use of addictive drugs for the space of 2 years, or has attempted the life of the other by poison or other means showing malice, or has been guilty of extreme and repeated physical or mental cruelty, or has been convicted of a felony or other infamous crime; or the respondent has infected the other with a sexually transmitted disease. "Excessive use of addictive drugs", as used in this Section, refers to use of an addictive drug by a person when using the drug becomes a controlling or a dominant purpose of his life; or

2. The spouses have lived separate and apart for a continuous period in excess of 2 years and irreconcilable differences have caused the irretrievable breakdown of the marriage and the court determines that efforts at reconciliation have failed or that future attempts at reconciliation would be impracticable and not in the best interests of the family. If the spouses have lived separate and apart for a continuous period of not less than 6 months next preceding the entry of the judgment dissolving the marriage, as evidenced by testimony or affidavits of the spouses, the requirement of living separate and apart for a continuous period in excess of 2 years may be waived upon written stipulation of both spouses filed with the court. At any time after the parties cease to cohabit, the following periods shall be included in the period of separation:

A. Any period of cohabitation during which the parties attempted in good faith to reconcile and participated in marriage counseling under the guidance of any of the following: a psychiatrist, a clinical psychologist, a clinical social worker, a marriage and family therapist, a person authorized to provide counseling in accordance with the prescriptions of any religious denomination, or a person regularly engaged in providing family or marriage counseling; and

B. Any period of cohabitation under written agreement of the parties to attempt to reconcile.