Uhh obsession does tell that story. Bar for bar.
spoiler
Did you miss the bedroom scene? It's like the most iconic scene of the movie, literally a dark room with her screaming, and the one time we undeniably hear from the trapped Nikki. But even starting from the car scene it's clear she's in there suffering.
100% not trying to dog on you, it's just that what you described is the very thing I loved the movie for.
Honestly I'm starting to think the film was designed to have a very clear feminist reading yet pull very different interpretations at the same time. It's master class. They shoulda called it Subversion.