The Ending
Sibel gave life to Cahit and Cahit followed her.
Taxi driver gave life to Sibel and Sibel followed him.
The movie is about "who gives you life?"
As a secondary thing: The movie also makes a distinction between women and men. For a man, it's a woman. For a woman it's a child.
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http://www.imdb.com/mymovies/list?l=15227539