Complex sentence: No matter how many people he is surrounded by, he feels alone mainly because he feels that they can't relate to him (ironically the only person who does is his nemesis, Lex Luthor).
Split into simpler sentences: No matter how many people he is surrounded by, he feels alone. This is due to the fact he feels that they can't relate to him (ironically the only person who does is his nemesis, Lex Luthor).