You're going to have to man up and talk to your wife. Based on the above, your issue is not a candidate for an order of protection under Illinois Law. The purpose of an OP is to protect people from danger, not annoyance. And since your wife is allowing him access to the house (I presume), I don't think you'd last 30 seconds in an OP hearing.
Ergo, roll of the sleeves, watch some Chuck Norris if need be, and talk to your wife about the problem.
Without an arrest, it is very unlikely that you can obtain a restraining order. You can try to get an order of protection, but you do not appear to have grounds. You may also attempt to put up a no trespassing sign and give him verbal notice not to trespass, but the problem with that option is that your wife is allowing him onto the property and has given him permission to come by. In that case the police may not do anything if you report him for trespassing. You should probably come to an agreement with your wife before taking any legal action.
The information in this answer is not intended as legal advice nor do I intend to create an attorney-client relationship with any reader simply by answering this question or contributing as a member of AVVO.