I'm not entirely sure specifically about this 'My Wife is Cold Hearted' light novel. But generally, in such stories, the cold - heartedness of the wife could be a front for deeper insecurities. The plot might revolve around the husband's attempts to break through that cold exterior and discover the real person underneath. For example, he could start by trying to understand her daily routines and interests more, gradually building a connection.
Well, it could be about a relationship where the wife is perceived as cold - hearted. Maybe she has some past traumas or a personality that makes her seem unemotional in the relationship. It might explore how the protagonist deals with such a situation in their married life.
The 'My Wife is Cold Hearted' light novel might be about the complex dynamics in a marriage where the wife shows little emotion. It could be set in a particular cultural or social context that influences her behavior. There could be other characters in the story who either exacerbate the situation or help the couple to reconcile their differences. For instance, a close friend of the husband might offer advice on how to handle the situation, or a family member of the wife might reveal some hidden aspects of her past that explain her cold - heartedness.