In the 'secrets of happiness novel', one secret could be strong relationships. Characters who have deep and meaningful connections with others seem to be happier. They support each other through tough times and share joys.
The novel might explore happiness through the characters' journeys. For example, if a character starts from a state of unhappiness and gradually finds joy, it shows how different experiences can lead to happiness.
I'm not sure specifically as there could be many novels with 'happiness' in the title. It might be about a character's journey to find happiness, or various stories that revolve around the concept of happiness.
The novel The Pursuit of Happiness was a story about a girl named Yang Xiaoxue who struggled from the countryside to the city. She finally achieved success and happiness through her own efforts and the spirit of not giving up. This novel also involved family, love, friendship and other topics. It was a novel with rich emotions and twists and turns.
I'm not sure specifically as I haven't read it. But generally, it could be about the concept of happiness deteriorating. Maybe it follows a character or characters who experience a decline in their happy states due to various life events like loss, disappointment or difficult relationships.