Sorrow and Bliss follows Martha’s journey with mental illness. A major impact this has on her life is how it changes her relationships with the people around her, especially in her marriage to Patrick and its eventual breakdown. Thus, one of the central themes of the book is the isolating nature of mental illness.
Martha experiences her first mental health crisis when she is 17, and finds herself unable to write an exam, taking shelter underneath the desk in her room for weeks. From this very first instance, Martha begins to push people away. When Martha begins taking antidepressants later that year, the side-effects see her lacking the energy or desire to spend Christmas at Belgravia as usual. Even when she is forced to attend, she spends the holiday alone in a room away from the others.
As Martha continues to deal with her mental health throughout her twenties and thirties, the picture that emerges is of someone not especially inclined to make new friendships or maintain existing relationships. Martha’s relationship with Patrick appears more hopeful than the previous one she had with Jonathan, as Patrick has been around for longer than Martha’s illness, and he has even seen her on her “bad days.