Severus stepped back from his door and invited Harry into his chambers. He was not jealous, he told himself. It was entirely expected that a teenager would explore his sexuality at the age of sixteen. Even if his master wanted to pursue a relationship with the Ravenclaw, they were still connected. Luna was not. She had told Harry that she would not accept his mark, and Luna Lovegood was not a person who changed her mind. Hence, there was no reason whatsoever for Severus to be jealous!