The theme of mystery also plays a role. The fact that the husband is hiding his beauty creates an air of mystery in the story. Readers are likely to be intrigued and keep reading to find out why he is hiding it and what will happen when his true self is revealed.
Love and acceptance could be another theme. Despite the husband hiding his beauty, the relationship between him and his partner might still develop based on true love and acceptance of each other's true selves. This shows that love can be more than just physical attraction.
One similar light novel could be 'My Next Life as a Villainess: All Routes Lead to Doom!'. It also has elements of unique character relationships and interesting plot twists. Another one is 'Kiss Him, Not Me', which shares the aspect of dealing with complex feelings towards a particular character.
One possible theme could be secrecy. The husband's mysterious nature implies that he has secrets, and the story might be about how these secrets impact their relationship and the main character's life. Another theme could be suspense. The mystery around the husband would create a sense of suspense as the reader and the main character try to figure out what he's all about. And family might also be a theme, as the marriage ties them into a family unit, and the mystery could be related to his family background or his role within the family.
Another theme might be self - improvement. The female lead may need to grow and change in order to fit into the billionaire's world, which could involve learning about business, etiquette, etc. Also, the theme of redemption could be there. Maybe the billionaire has some past issues or a cold heart that the female lead helps him to overcome.
Since I don't have in - depth knowledge of this light novel, it could be that the 'player' has a dark or complicated past. Maybe he was involved in some sort of scandal or had a difficult upbringing. The story might show how his past affects his current actions and relationships within the context of the light novel's world, whether it's a virtual game world or some other fictional setting.
Perhaps he has hidden the full extent of his Sage Mode abilities. He might be able to stay in Sage Mode for a much longer time than he has shown so far, or have some other undisclosed powers within that mode, like the ability to sense enemies from much greater distances.
The themes in this novel might include love against all odds. Despite the social stigma and family complications, the two main characters fall in love. Another theme could be self - discovery. As the characters engage in this relationship, they might learn more about themselves, their desires, and what they are willing to sacrifice for love. Additionally, the theme of social norms and breaking them could be explored as they go against the typical family relationship boundaries.
Family might also be a theme. Maybe the relationship of the couple is influenced by their respective families or they build a new family together. There could be stories about how they deal with family matters.
One possible theme could be the struggle for freedom. If a woman feels trapped with her husband, she might be fighting to regain her independence. Another theme could be power dynamics within a relationship. Perhaps the husband has more power, whether it's economic, social, or emotional, which makes the wife feel powerless and trapped.
Love and the perception of it at a young age could be a theme. He might have a naive or idealistic view of love that makes him want to be a husband. Also, the theme of change could be present. As he moves towards this idea of being a husband, he will have to change and adapt, both in terms of his behavior and his understanding of the world around him. This could be explored in the context of school, friendships, and family interactions in the novel.
Maybe he has some dark secrets in his past that he doesn't want to be known. For example, he might have been involved in something illegal or unethical that could damage his reputation in the world of the web novel.