It's a novel. The structure and style of My Happy Marriage indicate that it originated as a novel, not a manga. The depth of character development and the complexity of the plot are typical of a novel format.
The popularity of the 'my happy marriage free novel' can be hard to gauge without more data. However, if it has been translated into multiple languages or has a large number of downloads on free e - book platforms, that could be an indication of its popularity. Also, if it has a strong following on social media platforms where readers discuss books, it might be quite popular.
Another common theme is sacrifice. In a happy marriage within a novel, characters may make sacrifices for each other. This could be sacrificing personal desires or even career opportunities for the sake of the relationship. It shows the depth of their commitment to the marriage and to each other.
It's about a marriage that is happy. It might detail the relationship between the two main characters, how they met, and how they overcame difficulties together in their married life.