Complex sentence: Because of his unorthodox teaching methods, Lisa quickly takes a friendly, even romantic, liking to him; he is the only teacher, and perhaps the only adult, who has ever challenged, respected, and liked her.
Split into simpler sentences: Because of his unorthodox teaching methods, Lisa quickly takes a friendly, even romantic, liking to him. He is the only teacher, and perhaps the only adult, who has ever challenged, respected, and liked her.