A few things to consider in answering this question:
1. There is no per-se “common law” marriage in Illinois. If you entered into a common law marriage in a state that recognizes them, you may have some standing. Otherwise, in Illinois, one must be validly married, which means a marriage represented by a validly issued marriage license.
2. Generally, with regard to real estate, a piece of property can automatically transfer to another party in two ways: First, a legally married couple (see above) can hold their primary martial residence (the place that they call “home”) in “tenancy by the entirety”. This means that each spouse actually owns 100% of the property and can automatically take ownership of their spouse’s share when they pass on without any legal proceeding. Again, you need to be married (see above) to have this protection. Otherwise, two parties can hold a property in “Joint Tenancy with rights of survivorship” which means that the surviving party takes the share of the party who passes on. If the property is owned otherwise, then another party would need a legal action in order to take ownership.
3. That being said, there are ways to ensure that the property goes to another party who is not a joint tenant or a spouse. This is where an attorney can advise you with regard to proper estate planning, allowing the home to transfer to another party in a legitimate fashion. My best advice to you would be to contact an estate planning attorney who understands real estate law for guidance and planning in this area.