For those who might be interested, there is Jonah Goldberg's thesis in his recently published
Suicide of the West. Briefly: flavours of tribalism are the natural social and political organization of people; the principles and institutions of liberalism are not easy to come by and foster; only once in history (our current era) has (part of) humanity managed to find its current state of prosperity and liberty - Goldberg calls it the "Miracle" - by leveraging a critical mass of those principles and institutions; if tribalism is the mean to which everyone reverts, then liberalism requires constant upkeep and our status quo is (and always will be) unstable.
Everyone who supports a flavour of tribalism (populism, nationalism, class warfare, caste societies, identity politics, etc) is ultimately an enemy of liberty and prosperity; everyone who chips away at classical liberals until they throw in the towel and revert to the politics of tribalism is an enemy.
If the US is in the grip of populism and reverting more to the "us vs. them" posture, it is incumbent on the rest of the G7 to become less "us vs. them" until (hopefully) the US "recovers". But that requires acknowledging and defending the correct principles and institutions, and eschewing the politics of tribalism.