Do I have to keep paying Maintenance if she is living with a guy?

No. If your ex-wife (or ex-husband for that matter) is living with a new guy or gal in a conjugal relationship (sex), you have a reason to stop paying maintenance. The thinking in Illinois goes like this: she is no longer your financial responsibility, let the new person take care of him or her. That being said, you will want to have a court order stating that your obligation for maintenance is over. Sometimes your ex-spouse will agree to the entry of a court order to stop the support, sometimes not. You might have to prove that the new living arrangments of your ex is on a conjugal basis and not just a case of having taken in a roommate to share expenses, without that kind of a relationship. This can be difficult and the court will consider the circumstances such as how much time they spend together, joint activities, expenses, joint accounts, etc. Sometimes it will just come down to the individual judge. 

Get the Court Order so that you are protected. To discuss stopping court ordered maintenance, make an appointment at O'Connor Cadiz Law, located in Schaumburg and Itasca, Illinois.