A disagreement becomes more manageable when its history does not have to be retold at full length every time.

Some arguments are exhausting mainly because of the run-up. Both people feel they cannot make a point until the whole background has been recited, so every conversation begins three years ago and arrives at the present already tired. The history is usually not in dispute anyway; it is being repeated to establish standing rather than to inform.

Agree, if you can, to start from where you are. Say the current thing in a sentence and let the background stay assumed unless someone genuinely disagrees about it. If a fact from the past is needed, name it briefly rather than retelling the story around it.