Unfortunately for you @Van6457 I completely agree with what @Anonymous posted. In May..... everyone in the entire world knew more or less that covid-19 was here to stay for the long-term and that it would continue to disrupt travel of any kind. Since March...... even insurance companies do not consider covid-19 an "unforeseen" event and will not cover the type of situation you are in. If travel insurance refuses to cover you, why should the host be expected to overide their own cancellation policy???
It is the guest's responsibility to read and understand what the cancellation policy is and the implications.
I host a lot of people just like you, exchange students or interns coming to Seoul for 1~4 months. FYI, I had an inquiry end of March for a long-term stay with an early May check-in date for 3 months (for some sort of exchange program). I had no intention of hosting an international guest in my private room home due to risk of exposure and extra burden if the guest needs to self-quarantine for the first 2 weeks upon arrival in our home and explained why I could not host her. I also suggested to that guest to hold off on booking ANYTHING because I had been hearing that most schools, companies, institutions were planning to fully cancel any sort of international exchange program for the remainder of this year and the government would soon issue a *recommendation* along these lines - all of which did happen in April. I told that guest, if travel restrictions are lifted and we magically become able and comfortable enough to host and we happen to get an inquiry for any of the overlapping dates, we will message her to ask if she was still planning to come and would like to stay with us before accepting another booking for the dates she wanted.
While I understand how frustrated you must be feeling...... you really should have done your homework before parting with your money, *assuming* you'll get everything back if you cancel. I've voiced many times that I feel people who booked before mid~end of Feburary (for stays anytime during the remainder of this year) before the world realized how serious covid-19 is should get a full refund and refunding is the right thing for hosts to do. In your case..... you already knew the risks of covid-19 and decided to book anyway so imo, there is no reason for the host to refund you beyond the cancellation policy.