I must respectfully disagree, Q. There isn't an iota of evidence in the OP's posting evincing that a landlord/tenant relationship ever existed between OP and his erstwhile girlfriend! A legal relationship which clearly must exist in order for subsection (f) of Section 5-12-130 of Chicago's Municipal Code and its "seven day abandonment period" to apply.After a 7-day notice to remove the property has been given, the property can be considered abandoned if not removed. In Chicago.
The pertinent portions of that Municipal Code particularly apply to "property of a tenant" as one obligated under a "rental agreement" whom either "having abandoned the rental unit fails to remove his personal property", or fails to do so "after the termination of a rental agreement". Clearly it addresses the remedial rights of a landlord as to property of a tenant, not those of a tenant playing host to an invitee.
Notably no where is the OP contending that he sublet the unit to the girl. No where has he stated that any rent was paid during her brief and sporadic presence in the unit; nor is OP claiming that unpaid rent is due and owing. No where has he referred to her as a tenant or a subtenant.
Also of note is the fact that this seven-day-expedited remedy afforded to a Chicago landlord was not one permitted under common law. Consequently, the enabling code section must be strictly and literally construed and applied.
Unless otherwise declared by legislation, personal property is regarded to have been abandoned where there is a clear showing of the owner's intention to relinquish rights of ownership coupled with a physical or outward act by the owner demonstrating that intent.
Here we have the physical or external act of relinquishing physical possession and control of the goods. The remaining issue is whether or not the required element of intent to abandon has been effectively demonstrated and demonstrated in spite of the latest communication between the parties. However, no unheeded- seven-day-notice - as you have proffered - will suffice in substitution for that needed element.
Interesting topic as the subject of the abandonment of personal property seems to be forever marked with discord. Something Chicago's City Council attempted to alleviate, but only as between landlords and tenants; not tenants and their guests.
Personally I think the evidence of intent to abandon has been shown by the owner's failure to retrieve her goods within the past two months. But to solidify it I would have the OP formerly demand that the goods be reclaimed within thirty-days from date of demand or he will consider them as having been legally abandoned and at his disposal. (And if possible under a letterhead of an attorney at law.)