What happens if a partner wants to leave the partnership?
Hopefully you have a partnership agreement. If so then, you have a clear path to the termination of a partnership.
If not, both parties need to agree, if at all possible, on a few things. Depending on the length of the partnership there needs to be a financial agreement on who gets what and how much.
Finally, there will need to be a termination of financial obligations and commitments that may extend past the partnership termination. Are there loans or rental agreements signed by both parties? Simply put, if one partner walks in one day and says “I am done” that does not necessarily entitle that person to avoid financial prior commitments.
Also, there is no rule that the person leaving the partnership deserves anything if it has not been agreed upon so this may need to be handled by a mediator or arbitrator.
It is a divorce and they typically are messy.