@Karen3131
@Sandra856 Is spot on.
Note that you are under no obligation to accept a date change request from a guest. A date change generally benefits the guest, not the host (a penalty free cancellation essentially). It’s also a good idea to set a limit to how many times you will allow a change, if you do, at the time of request. No more than once is advisable.
This guest is putting out red flags, and your suspicion is likely right that they no longer wish to stay, at all. The sooner you get this booking off your calendar the better, so that you can get the dates filled, and this person out of your hair. You might strongly encourage the cancellation along by offering to let them out of the cancellation policy they agreed to (long term policy) IF and ONLY if, they cancel immediately, to open your calendar.