I think it's more subtle than that, and somewhat more understandable.
Some people, for good reason or bad, will rarely be represented by a majority rule vote. These people have little reason to support, and plenty of reason to reject, government based on majority rule. This is the core problem of democracy.
The Founders sought to address this problem by strictly limiting what government can do in the name of majority rule. That gives some assurance to minority voters that they won't simply be slaves to the majority, that their rights will remain intact even if the majority disagrees with them. It makes it possible for the losers of a given vote to say "well, we didn't get our way this time, but there's only so much damage the other side can do, so we'll accept it for now."
If voters lose confidence in the Constitutional limits on government power, they can no longer accept majority rule. I think that's a large part of what's going on with the divide. Neither side can accept defeat.
A lot of it is also systemic, due to innate flaws in plurality voting, things that various reforms like RCV could address. But we have to have enough unity to pass those reforms, so ...