Why does he give me a last glance when he leaves the class if he is not into me?

He often turns around to glance at me when I’m distracted. By now it has happened so often that his friends are annoyed. Since he never gave me any clearer signs I guessed he was just bored or slightly attracted but not interested enough to approach me. One day I decided to stare back at him from behind (I always sit in the back of the room) and he somehow noticed it through the periphery, got jittery and tried to purposely look away. When class ended he gave me a quick glance and followed me to the subway Station where he stared at me from the other side. Things like this happened frequently over the course of 2 years but after confronting him with it he denied it very bluntly, saying he was never that interested even after I admitted that I stared at him quite a bit. Why does one act this way if not interested? I’m not that pretty to be this soothing to the eye

Why does he give me a last glance when he leaves the class if he is not into me?
Post Opinion