Sexual orientation and gender roles
Farewell My Concubine does some interesting things with Douzi's sense of gender and orientation. Broadly speaking, it seems like he feels unable to be himself, and his homosexual attraction to his friend doesn't help. Although the line, "I am by nature a girl/boy" confusion in the novel may seem tangential, it actually might be an artistic device, explaining Douzi's perplexing attraction to his co-actor. Basically, it would be alright if he was a woman, but Douzi doesn't feel womanly. He feels like he, as a man, wants to be with another man, and that isn't something that his culture tolerates.
Vocation forms the sense of self
By confusing the reader with three and four different names for some of the main characters, the writer shows how our daily work forms our sense of self, and so for a professional actor or performer, the act of pretending to be other people does have the same effect, and it's not clear that the characters in the novel are left with clear boundaries around where the art begins and where their 'self' stops. They bleed together.
The Communists as tactless and brutal
When the Red Guards enter the story, their interests don't preserve the delicacy of the environment, and this causes a serious paradigm shift. Sadly, not all the characters transition to the new economy well.
Feminism and the problem of prostitution
Yes, the title of the novel is a reference to a play performed within the novel, but Farewell My Concubine is also a wise title for the story, since the novel indirectly criticizes society's perception of prostitution. The novel does this by outlining a plot where concubines are focal people in the plot, and where their prostitution is shown as an unfortunate fate.
Instead of viewing prostitutes as criminals, tempting men and committing indecent acts, the novel draws attention to their quality of life, the desperation of their situation, and how little resources there were for women during this time in China. Prostitution is not something that women do to harm men, not in this story at least. If anything, it's a reflection of society's misuse and mistreatment of women, especially poor women without the means to take care of themselves.
