Oh dear! You've done the equivalent of taking your wife to a jewellery auction and sitting in the front row; there you'll get the piece after being chased up by dealers in the room who all stand at the back,bidding just for a lark because they know you'll buy it for her, and finished off by bids from the chandelier, as we say (meaning bids by the auctioneer himself looking up as though seeing bids when none are being made; that's why the dealers are at the back, to spot and stop that when they are bidding).
But all is not lost. If you were a billionaire , knowing that wouldn't affect the agent but being keen will cheer him. You have to know what the property is worth in these circumstances, leave your offer on the table and allow a bit for vanity when the vendor comes back. Then you add the vanity bit of a few per cent and say "Now I'm being generous, your vendor knows that, but I've had enough and am walking away, if he doesn't want the cash. Thanks for your help" You can add that circumstances have changed, that you are chasing another property, if you like.
The consolation is that you are probably be proved to be buying it cheap enough, when the market picks up. We've all bought property too dear in our time but been consoled by that fact, if we're buying to live in it