Dislocation is likely a symptom of his mindset; Paul has had to become a creature of pragmatism, locking his emotional reactions into one purpose to ensure his survival. In civilian life, one need not be on guard 24/7, but Paul has forgotten this, and thus has difficulty with "ordinary" people, who cannot understand his experiences -- he no longer "belongs" in this safe, ordinary place.
Paul has had in so many ways to cease living a normal life in order to survive the brutality of war. This is something that is made clear in the earlier chapters. When he has the opportunity to go on leave, therefore, he finds he cannot disconnect from the lessons that war has taught him. This makes it impossible for him to reconnect to "normal" life and to pick up his normal relations again where he left them off.
One quotation emphasizes how distant Paul now feels from civilians. Indeed, he even feels a kind of contempt for them, since they have little idea of -- or little interest in...
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