Clarify what leaving means: stopping work, leaving management, selling ownership or obtaining liquidity. Review the relevant corporate documents before assuming which routes are available.
Understand the basis of value before negotiating payment arrangements. A staged purchase, a new shareholder, reorganisation or another transaction may deserve consideration, but none should be presumed feasible without analysis. Protect operations while discussions continue. The exit must address the responsibilities, financing and ownership arrangements of those who remain as well as the departing partner's objectives.