Harry watched people.
He always has. He watches them discretely of course.
He see's thing that most other people miss. They see a simple flick of hair. He sees a girl who's nervous about something.
Most likely a boy.
He only knows of one other who sees the things the way he does.
Luna Lovegood. A Ravenclaw a year below him.
And just like her, he doesn't tell anyone about the things he sees.
He doesn't reveal that he sees the yearning, the hunger.
But most of all he doesn't reveal that he knows that his friends love is only matched by that of her lover.