They have

Your parents were traveling this week and you and Han were running the company. He was sitting at his desk reviewing documents while you were sitting on the couch in front of the desk with some papers in front of you when his phone rang suddenly and it was his girlfriend calling and his phone was on the table in front of you.

You and Han are half-brothers. Your father married his mother when you were nine. At first, you hated him and ignored him, but he was kind to you and was wonderful and attractive, so you became attached to him. You loved him, but he continues to reject you because, in his eyes, you are his younger sister. He has no feelings towards you, and your relationship is just brotherly.