This novel could be interpreted in many ways—actually that's one of the best aspects of the book, that it addresses many issues, but without a moralistic attitude. The challenge of the novel is to interpret the difficult symbolism and plot structure, and what one will find is that certain aspects of the story matter to them more than others. For instance, someone might find the most important aspect to be the feminist criticism of the Chinese culture, especially around the issue of prostitution. Another person might find that the most meaningful aspect of the book is the resilience of Douzi in spite of social pressures to conform to a gender role that Douzi doesn't want. Yet another person might say that Douzi's attraction to his friend Shitou is at the center of the novel. For the purposes of this analysis, let's take a closer look at the last one, because it ties some of the others together, and structurally, it seems to have the most to do with the climactic moments of the novel.
Douzi is the (practically orphaned) son of a helpless, poverty-stricken prostitute whose disgrace leads her to more-or-less abandon her son into the care of an abusive man. A Freudian might comment on the Oedipal elements of this plot, Douzi now stranded without the female element of his self, his mother, and his confusing relationship with the abusive male figure in his life is just more fuel for that fire.
So this story is about a character without proper gender roles, since his childhood was kind of terrible. This makes him a good choice for the female lead, in Master Guan's eyes, and suddenly, Douzi feels an enormous pressure telling him to identify as a woman. This might be a metaphor for gender dysphoria, but in Douzi's case, it seems like it is being imposed on him by a society that doesn't understand his blooming homosexuality, and to make sense of it, Douzi plays it out on stage as if he were a girl.
The final moment in Douzi's character development is unfortunately the final moment of his life too. By still asserting that he is a man, he takes a final stand against the tyranny of society and the forces trying to make him feel like he should feel ashamed for who he is, and that he should change somehow. He takes that final stand, a move regarded in the context of the play as a mistake, but then he kills himself. He kills his real self, not just the character. This tethers him to his real problems of identity, and it ties his life as a character on stage back to his struggle to understand himself.
Ultimately the novel is a tragedy, but it bears noting that in the context of the novel, two additional factors drove Douzi to this issue—firstly, the rise of Communism, and secondly, the insufficiency of state resources for the lower class in China. The novelist asks us to consider Douzi as a hero, but also as a victim of social injustice.
