One possible theme could be the power of hope in the face of extreme hopelessness. Even though it's about suicide in the title, it might show how a glimmer of hope can change a person's perspective. Another theme could be the role of communication. Lack of communication or miscommunication can often lead to feelings of loneliness and despair that might contribute to suicidal thoughts. Additionally, it could explore the idea of self - worth and how a lack of it can be a factor in suicidal ideation.
It could potentially explore themes of despair, isolation, and the search for meaning in life. These are often associated with the idea of suicide.
Maybe it will touch on themes like the breakdown of social support systems. People who feel isolated from family, friends, or society are more at risk of suicidal thoughts. So the novel might look at how that situation develops. Also, it could deal with themes of mental illness and how it can lead someone to consider suicide as an option when they are in the grips of depression or other disorders.