Spoiler level: High. If you haven't seen the movie, don't read this piece.
Why did she do it?
This is perhaps the biggest question that people asked after watching the film. Why did she do it? There are indeed several interpretations, all possibly true. A romantist would say it was love. Love is blind! Love is crazy! A biologist would say it was the hormones. Once she saw that big bling, her glands produced chemicals that disturbed her rational thinking. Whatever dude, there's a reason why I dropped my bio major.
A couple of days after watching the film, I came across the original short story in a bookstore. At the end of the story, there was an essay written by the scriptwriter answering this question. The details of his essay are quite blur, so I'm going to paraphraze like crazy. I might be misinterpreting him, but I don't give a damn. According to the scriptwriter, her act poses many questions to the audience. The audience is left puzzled, and does not clearly know her intentions. This was the precise effect the writer wanted. By depicting an unexplicable act, the author wanted to show that some things in life are just unexplicable.
I think that a part of it was all that the others have said - the feelings she developed for Yee, through a combination of intimacy, Stockholm Syndrome, lust, love, empathy, feeling that she was important and precious to him, call it whatever you want.
But there's also another aspect. She was manipulated, used and abused throughout the story, but not just by Yee. He abused her physically, but her own co-conspirators - her friends, including the guy she had been in love with, and the older ringleader guy - had been using and abusing in an even worse way, even though it was an abuse she agreed to, in the name of patriotism. It's a moral ambiguity at the heart of the film: on one hand, there is a story about patriots and traitors, but then it's also a story about the way young women are treated like sexual commodities, and it doesn't make the patriots in the film look good. They all acted like it was completely acceptable for her body to be used sexually in the name of their cause, and never stopped to think that how that might affect her, that she was a person (and a very young, inexperienced, vulnerable person as well) and that she might get psychologically affected by it. When she talks about her feelings to the young-leader she was in love with and the older ringleader (sorry, I saw the movie a few years ago so I forgot the names), they are both visibly uncomfortable and trying to ignore her speech, as if they just don't want to know. At least Yee is open and direct in his abuse, and eventually she starts feeling that he cares about her more than the others do (as we see in the ring scene, when she realizes that she did something for her he never did for his wife). And since she was basically being prostituted by her co-conspirators, she also might have felt some empathy for Yee's feelings of isolation and his own self-imposed position as the "whore" of the Japanese, as he put it.
Finally, I think a big part of what she did it was also because it was the only thing that she could do out of her own free will. Up the that point, she had been fulfilling the role that had been set out for her, doing what she was supposed to do; her final act was, consciously or subconsciously, the only act of defiance, the only choice she could still make on her own. Even if it resulted in her death.
Pain is to pleasure as disco is to punk.You need to live through one to fully appreciate the other.
'Finally, I think a big part of what she did it was also because it was the only thing that she could do out of her own free will. Up the that point, she had been fulfilling the role that had been set out for her, doing what she was supposed to do; her final act was, consciously or subconsciously, the only act of defiance, the only choice she could still make on her own. Even if it resulted in her death.'
-- AMEN! i too felt this as well--it was the first, the ONLY decision she made for herself.
I have read the comments and a lot of people are still discussing on what made Wong Chia Chi/Mak Tai Tai did at the end of the film.It was apparent that many did not understand the reasons of her actions at the end. People may find it weird or disgusting BUT it apparently has to do with the psychological make-up of Mak.
First of all,we have to realize that Mak isn't a professional spy.She is a naive college student whose view of the world is not within the context of the people that she deals with when socializing with the Japanese collaborators while doing her work for the resistance.Also,it was clear in the film that she lacks a father figure as her dad left for England and got remarried while her mother died when she was very young. She found a father figure in Mr. Yee. Aside from that,Mak lacks experience in intimacy which can deepen a relationship with certain individuals. Mr.Yee was able to provide this to her through passionate (and rough) sex. That is why the sex scenes were important to demonstrate this to the audience. Finally,she was drawn to Mr Yee due to the latter's charm - a characteristic of people who rise to political ranks and find success in dealing with others in the government despite their actions of cruelties towards their countrymen. I believe that even the likes of Hitler and Stalin did possess charm and charisma to have become successful leaders and were effective in leading their people in doing evil deeds towards humanity.
In the end,Mak sufferred from Stockholm Syndrome which made her save Mr Yee at the end of the film. IT WAS NOT BECAUSE OF HER BEING A WOMAN BUT DUE TO HER PSYCHOLOGICAL MAKE-UP AS A WOMAN.
Ivana, you make important points I have skipped over as I hastily reflect on this movie. Yes, she is used and abused. The movie points out the irony of such student movements--it is the men who make the decisions among themselves and employ the women as objects. Having talked with many women living through the sixties, on a much more benign level, this held true--The women of SDS made the coffee while the men played at being revolutionaries.
You also make a wonderful connection between the two characters, both of whom a you say, feel isolated, "pimped," though it could be said they pimp themselves out.
And finally you see her choice at the end in a kind of existential way I'd not at all considered. She finally does "act," at least out of a genuine feeling, as a subject rather than an object, although this costs her "friends."
In the end we see that their actions were an inevitable part of their very different characters. He was willing to sacrifice her while she sacrificed herself and her allegiances for him. After all, he is a traitor to his country, while she endangers herself out of loyalty to friends and country. When we trace the outlines of each from the start of the story, we see that what is revealed in this ending has been there all along. Who said "character is fate?" I don't remember, but many works of fiction work this way--not through "character development," but rather,through showing us the inevitability of character.
To return to the question of whether he loved her--I don't think he could love another person in the sense of putting someone's welfare above his own. He could be moved, infatuated, sexually obsessed, but in all his dealings his own desire for power came first. He would, at any cost, survive.
She was not "built like that," (my grandmother's expression). She was fully capable of friendship,love,loyalty. Now, that she "betrayed" her friends--I don't believe she deliberated or premeditated the betrayal. She simply in the moment could not help but warn this man she had allowed to get into her mind and heart.
That is all not to say that he was a pure unfeeling monster or she a sainted victim. The nuances, shades of gray, make the movie a complex experience, one that lingers and presents us with questions to which there are no answers, only the inevitability, the fate that is foretold in character.