The short answer is "No".
You only have to fulfill what you've currently signed contractually.
During "option period" you might expect some requests for changes if they are in regards to something that was not on your sellers disclosure but are significant to market value of the home.
Additionally, term flexibility might be in your best interest as well, say, if a buyer needs a couple more days here or there for processes.
See, pick your battles and be realistic on pricing or repairs during renogatiations because your next buyer will most likely have similar requests....
The difference in the next buyer is that they will come in with less value perceived than the first buyer. Why?
Well, one buyer walked away already for an unknown reason to the next buyer... and, you must disclose new knowledge of the home.
Collectively, this rarely starts the next buyer at a higher price than the first.
This is a matter of strategic positioning for not only a win-win, but loss-prevention.
If you have a real estate agent, ask that agent to bring in his or her Broker for a third pair of eyes to oversee the situation as a safety to ensure one aspect doesn't go overlooked.
If don't have an agent, call this emergency realtor service and engage immediately:
512 - 663 - 4686