If both parties no longer desire an agreement, there isn't one.
At some point holding even one party to an agreement they really don't want to be part of just isn't workable. By fielding an army for the purposes of rebellion, the South unintentionally formed the conditions for keeping them in the Union: military defeat.
The left has conquered this nation and subverted its constitution and laws precisely by never creating and confrontation or conditions that could lead to their defeat. They simply kept selling their ideas and gaining ground in the institutions (schools, media outlets) that could promote their ideas until they had a critical mass of thought on their side. A majority of the federal budget now goes to essentially buy votes for their way of thinking.
They did all this by never admitting what they were really up to and by strategically undermining everything that made this nation what it was.
We have been trying to conserve what was left of freedom and the rule of law, and some will continue to do so until all they are conserving is words on pages in history books. That is a defensive war, doomed to failure.
We must start to act and think in terms of gaining ground. We have to be subversive to their goals, constantly attacking the political left's underpinnings, taking out their power base and salting the very institutions they are using to promote their ideals. Part of that strategy has to be strategic withdrawal. None of this is in any way violent -- violence opens the possibility of losing to a superior force. The idea of secession is powerful. It is worth considering that if we keep on our present course it won't be long before there won't be anything to secede from.
Agreements have their methods of resolving disagreements. Unions have them too. Rather than have the King of England resolve local disputes (that didn’t work out well for Scotland) a federal court system was instituted.
The rebels sought to resolve issues on the battlefield rather than in court. They lost.