All sorts of things happen in real estate, and as agents we often tell clients that it isn't sold till it closes and to celebrate then.
I have also found that buyers always want to know why a property came back on the market when something does arise that prevents settlement. Buyers fear that it might the result of a home inspection, and if that buyer pulled out maybe they should not make an offer.
Sometimes it is not the house's fault a sale falls apart, something else can prevent a buyer or seller reaching settlement or closing.
It can be the result of buyer remorse, a redistricting by a school district, the township not allowing sub-division on a large property, or maybe not allowing for a garage to be built, potential from proximity of neighbors being on the Megan's Sexual predator List, a rise in interest rates causing the buyer to no longer be able to afford the mortgage, and as I mentioned before non payment or filing of taxes that now must be paid.
I recently had a client interested in a home, it met their parameters and they wanted to know why the house had come back on the market. Calling the listing agent to ask some questions i added why did the house come back on the market? She went on to tell me how wonderful the house was, and how it had sold quickly before, but the buyer's wife had had a cardiac situation and had not survived. The buyer requested release from the contract and the seller had agreed.
Whilst the PA agreement of sale actually has a section dealing with situations like this and it requires heirs to go to settlement, it was very kind of the seller to allow the buyer to be released from the settlement and luckily for them the market is strong enough that the house will sell again very soon.