One possible theme could be regret. Looking back at a past relationship often involves thinking about things that could have been done differently.
Another possible theme could be forgiveness. The husband may have to forgive his wife for her past actions, and the wife may also have to forgive herself and move forward in life.
One possible theme could be devotion. If a wife is considered as one's life, it implies a high level of commitment and loyalty. Another theme might be the significance of the relationship in shaping one's identity. Since the wife is equated to life, she probably has a major impact on who the person is.
Another theme might be the passage of time. As the story unfolds, we could see how time has changed the character, their relationships, and their view of the world. It could also touch on themes like resilience, as the character overcomes various difficulties in their life journey. For instance, if they faced a tough childhood but managed to build a better life for themselves later, that would show resilience.
One possible theme could be self - discovery. In a mysterious life, the main character often has to figure out who they really are.
Love and loss could be themes. There might be relationships that are affected by the twists in the character's life. They could lose someone they love or find new love in unexpected ways. Also, the theme of fate or destiny could be present. The twists could be seen as events that are meant to happen, guiding the character's life in a certain direction.
Love and its aftermath could be a major theme. After the break - up, the characters may still have lingering feelings of love, but also feelings of anger or hurt. The novel might also explore the theme of change. The change from being in a relationship to being an ex is a significant one and can affect many aspects of a person's life, such as their daily routine, their social circle, and their self - identity.
One possible theme could be the struggle for self - identity. In a ruined academy life, the main character may be constantly trying to figure out who they are among all the chaos. Another theme might be the importance of friendship. Despite the ruined situation, true friends could be a source of support.
Another theme could be privacy itself. It may show how the sister tries to protect her private space and what happens when that privacy is invaded. It could also be about self - discovery. The sister may be on a journey to understand herself better in her private life, away from the outside world's expectations.
I'm not sure specifically as I haven't read it. But generally, it might be about the past life related to an ex - perhaps memories, experiences shared, or the process of getting over an ex.
One possible theme could be growth. Just like a tree starts small and gradually becomes large and strong, it can symbolize personal growth. Another theme might be endurance. Trees face all kinds of weather and still stand, similar to how people endure difficulties in life.