Her name on the deed or not makes no difference in IL when it comes to divorce.
PROPERTY DISTRIBUTION:
Illinois is an equitable distribution state, meaning that marital property shall be divided equitably, not necessarily equally. For purposes of distribution of property, all property acquired by either spouse after the marriage and before a judgment of dissolution of marriage is presumed to be marital property, regardless of whether title is held individually or by the spouses in some form of co-ownership such as joint tenancy, tenancy in common, tenancy by the entirety, or community property. Marital property shall be divided, without regard to marital misconduct, considering all relevant factors, including:
The contribution of each party to the acquisition, preservation, or increase or decrease in value of the marital or non-marital property, including the contribution of a spouse as a homemaker or to the family unit.
The dissipation by each party of the marital or non-marital property.
The value of the property assigned to each spouse.
The duration of the marriage.
The relevant economic circumstances of each spouse when the division of property is to become effective, including the desirability of awarding the family home, or the right to live therein for reasonable periods, to the spouse having custody of the children.
Any obligations and rights arising from a prior marriage of either party.
Any post-nuptial agreement of the parties.
The age, health, station, occupation, amount and sources of income, vocational skills, employability, estate, liabilities, and needs of each of the parties.
The custodial provisions for any children.
Whether the apportionment is in lieu of or in addition to maintenance.
The reasonable opportunity of each spouse for future acquisition of capital assets and income.
The tax consequences of the property division upon the respective economic circumstances of the parties.
http://divorcesupport.about.com/od/usstatedivorcelaws/a/illinois_laws.htm