I can't address the particulars, but in almost every case when two friends or colleagues develop an intractible dispute, the following origins can be observed: one party did something in good faith that they believed was right. The other party experienced fear, when they observed an action that they did not expect from a friend or colleague which triggered memories of other hurts in their own past, followed by anger, when instead of going to their friend/colleague in openness and vulnerability to express their confusion and concern, they instead equated their friend with someone who they trusted who hurt them in the past, causing them to interpret that action as a betrayal and leading them to actually be the one taking the first actual act of betrayal and hostility, but to them it just feels in their gut and heart that they are protecting themselves and what they love from the enemy within. Of course the original party feels attacked and betrayed when the second party choses to make them an enemy instead of giving them the benefit of the doubt.
Wars, divorces, and schisms usually occur this way, as the contagion of misunderstanding to prejudgement to hostility to reaction to escalation spreads.
The trick is at the start the first party could have been right or wrong and if approached as an ally instead of a perpetrator would probably have been able to work out a follow up action that would satisfy the needs and concerns of both parties.
A Zen negotiator helps each party get to an understanding of facts they know and separates it from the layer of assumptions and suppositions they are taking as fact. Then helps each own their own emotions, needs, and contributions to the problem, finally helping them both to see each other as basically good and trustworthy people who make mistakes and deserve the benefit of the doubt, so they can approach each other with humility and compassion, forswearing the urge to punish or marginalize.
