I think this might also be related to the difference between patriotism and nationalism. I've recently seen a bunch of memes about how patriotism is wanting your country to be the best it can possibly be, while nationalism is believing your country is best no matter what. The former is a drive to improve and to fix problems, while the latter means that any constructive criticism is taken as hostility. (I'm aware there are other definitions of these words, but this is the one that works for me in exploring this issue.)
A blind belief in the infallibility of the thing or person you support, will easily turn toxic. It's not a healthy kind of support.