Complex sentence: However, he decides to leave the X-Men at the conclusion of the game as he feels that he is fundamentally a man of peace, with Xavier respecting his decision and assuring Kurt that he will always be welcome at the school.
Split into simpler sentences: However, he decides to leave the X-Men at the conclusion of the game as he feels that he is fundamentally a man of peace. Professor respects his decision and assures Kurt that he will always be welcome at the school.