Thank you for asking. Sure I'll try, hopefully without writing an essay.
First, my POV is that the nation-state is the top level geopolitical entity that I'm comfortable with. International co-operation can be a good thing, it can be virtually essential in some areas but it is just that, inter-national, nations should decide whether they co-operate or don't, to what degree, and how.
The EU, in my view is supra-national, it has taken on more and more of the features of the nation-state over time. It has a bank, a parliament (of sorts), a President, a court etc. As the EU has gained in power and influence, it seems to me that most of it's member states have weakened. The people who live their have less control over what their government does and those governments themselves have less control as they have ceded competence in many areas to the EU.
That's why I think it's alien. It is taking power away from my government and taking power away from me, I don't like that and I don't want it. I have a tiny, tiny amount of power and all the EU ever did for me was to dilute it further.
I want power to be exercised closer to those whom it affects, not further away. The people government must be able to get rid (wholesale) of the people elected to govern them. In the EU, obviously that can't happen because it's supra-national.
The EU presents as progressive (even benevolent) but IMO it isn't. It's a way to entrench further the power of those who already have power. Were it a common market into which everyone could sell but bascially nothing else, I'd be fully supportive, but it hasn't been that for around 30 years.
My other point is that, simply, many of these people are not our friends. America is, Canada is, Australia is, some individual EU Member states might well be but the major power players, no, absolutely they are not.
By chosing to align itself with the EU, the U.K. has spent decades putting distance and barriers between nations and peoples who are really our friends and allies in favour of cozying up to nearer neighbours who say they are, but are lying. That's why I feel alienated. I could write more about alienation in the .U.K. but that'll do for now.