Hi there, Henry. Not being able to easily cancel may have something to do with how much (little) time is left before your booking date begins, or perhaps because you live in the same Country as the Country in which the booking is supposed to take place? I thought that any guest outside of Germany would be able to cancel their reservation automatically due to the Corona outbreak? I'm not sure, but my wife and I had a reservation as well (end of August) in the Netherlands which I canceled due to not knowing how things will progress with Corona. (would it help to drink Corona beer)? 😉 In my reason for canceling, I used the option for "special circumstances" and was able to cancel without a problem. We're only getting a refund for about 80% of our paid amount though. If you're not a resident of the Country where the booking took place, then canceling should not be a problem. But if you are living and booking in Germany, then technically nothing prohibits you from taking advantage of your reservation.
Consider this ... it's not your hosts fault that your girlfriend can't travel to Germany.
The conditions to book, as far as the host may be concerned, were not based on the ability of your girlfriend to travel to other Countries. The agreement is between you and the host ... not your girlfriend and the host. 😞