Your seller changed his mind in the 11th hour. The deal is gone. Not on pause, but dead. You have sunk $100k+ of dead deal expenses.
But what if the seller comes back again a few weeks later? They change their mind, again. Now they're ready. Do you re-engage?
Probably not. Now is your time to wave goodbye with one finger.
An acquisition is also a partnership. Even if they do not roll or have a role on a go-forward basis, you will still need their buy-in for the transition of employees, clients & other stakeholders. Trust is essential in a partnership.