Can a seller cancel an LOI if the buyer misses an agreed milestone?

This depends entirely on whether your LOI actually ties specific consequences to specific milestones, since milestones written into a non-binding framework don't automatically create an enforceable right to cancel just because one is missed. If the LOI explicitly gives either party a right to terminate — including ending any exclusivity commitment — when a defined milestone isn't met by a set date, that language is what actually lets you cancel cleanly.

Where the LOI is silent, or describes milestones only as general expectations rather than conditions with stated consequences, a seller may still have practical room to walk away, precisely because the underlying deal terms were non-binding to begin with — missing a milestone doesn't need to be treated as a formal "breach" to justify losing confidence in the deal and stepping back. The complication is exclusivity: if that clause isn't tied to the same milestones, walking away from the deal itself doesn't automatically release you from exclusivity's separate stated period.

Building explicit milestone-and-termination language into the LOI from the outset avoids this ambiguity entirely. A Treadstone business lawyer can draft milestones that actually connect to a clear right to cancel, rather than leaving the consequence of a missed one open to interpretation.