Read the passage given below and pick the option that best fits the question that follows:
The unpleasant feeling passed and she glanced guardedly up at him. He was walking unmarked in moonlight, innocent of her reaction to him. She felt then-this thought had come to her before-that there might be more to him than she had imagined. She felt ashamed she had never thanked him for the help he had given her father.
She was ashamed because ________.