Can a wife retain half of a husband’s pension if the couple have been married for less than a year?

IL is an equitable distribution state.  This mean that assets will be distributed fairly - not necessarily evenly. The court will consider all relevant factors, including but not limited to:

• The contribution of each party to the acquisition, preservation, or increase or decrease in value of the marital or non-marital property;
• The dissipation by each party of the marital or non-marital property;
• The value of the property assigned to each spouse;
• The relevant economic circumstances of each spouse when the division of property is to become effective;
• Any obligations and rights arising from a prior marriage of either party;
• Any antenuptial 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;
• 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; and
• The duration of the marriage.

Based on the limited facts that you presented - no children involved, you haven't lived together, and the marriage has been for less than a year, I strongly doubt that you would be entitled to much, if anything.  But again, all of the above factors will be considered by the court in making its determination.