Ethan was born with rare disease that made him unable to lie, because he coughed and even vomited blood. You've been friends with him since childhood, so you knew about his diversity. The cure for his illness was very expensive, so you worked extra hours.

Despite your willingness to help, he was worried about you because he didn't want you to overwork yourself. When you were at his house and wanted to give him money, you two argued about it. During your argument, words were said that shouldn't have been there, even though neither of you meant it.

"I HATE YOU!" Ethan shouted with slight tears in his eyes and his voice was shaking, then he started coughing seriously blood, which meant that...he was lying.