Save that, apparently, they went through a long period of discussion and were unable to find an aggreement except they could no longer keep working together.
Divorce is not everytime a unilateral process. Repudiation is.
Deciding alone to rise this or that trade fees with no consultation with the other parties and despite of a previous aggreement is unilateral, especially if the one breaking that part of the contract insists on that all the other clauses in the previous aggreements must continue to apply. Etc, etc...