Can the polarization between Democrats and Republicans in the U.S. be reversed?

[Angrboda]

I'm reading the book "How Democracies Die," and it points out that laws and constitutions by themselves are not sufficient to safeguard democracy and rule of law, that these institutions depend upon the adherence to certain unwritten laws that help keep things running smoothly and orderly. One of these unwritten laws is that it's okay for the other guy to win, that our opponents on the other side of the aisle are not a life or death threat to our existence, that life will go on if they get their way, and that we eventually will get ours, and that is just fine. The polarization of politics in this country appears to be undermining that unwritten rule. The more we view the other side as a threat to democracy and the country, the more we are likely to view winning at all costs as acceptable. Viewing things in this way, we engage in unfair ways of achieving our victories. A common example is gerrymandering. It's frequently reported that Republicans have engaged in gerrymandering, but it's overlooked that Democrats do the same thing. The only reason Republican gerrymandering draws so much attention is because far more state legislatures lie in the hands of Republicans than Democrats, so Republicans have more opportunities to engage in it. But once both sides have committed to unfair means of winning, defeating the opponent by equally unfair means becomes justifiable and the abandonment of fair and proper means of political action becomes more common. When that becomes more common, each side begins to see each other as more of a threat because of their norm-breaking behavior, leading to even less fair behavior to prevent their achieving power. Thus an abandonment of tolerance for the opposing parties views becomes a death spiral in which more and more extremes of opposing them are justified because they are using more and more extreme methods of gaining power.

Polarization leads to intolerance. Intolerance leads to defections from the norm. Defection from the norm leads to more polarization.

How can the death spiral that occurs when polarization and intolerance become the norm be averted? Can it be averted?