When I started on airbnb, some potential guests sent enquires and often, nothing more was heard back from them.
Sometimes, after the visit dates had passed, from my curiousity, I clicked back on their profile checked to see if and where else they decided to stay - maybe I could pick up some understanding I thought. Sometimes they did have a review left, more often there was nothing more so perhaps they didn't travel, chose a hotel instead or decided not to leave a review- who knows? Very rarely will someone explain why they are going somewhere else, and there is no obligation to do so.
Anyway, I think it is quite typical for the communication to stop abruptly. Sometimes Airbnb send a message that the 'guest no longer requires accomodation for these dates'.
It may seem annoying but it's part and parcel of airbnb. Don't take it personally, because it's not you - it's other people and you just can't control what other people do or how they decide to conduct themselves.
You may do this already, but I suggest to have some saved replies ready or a bank of answers where you can cut and paste a reply efficiently. Do your reply then immediately archive the incoming message. Then just fuhgeddaboudit.
If they look, they'll look - if they book, they'll book.