Kal Ho Naa Ho had the same theme of Kuch Kuch Hota Hai, that "Pyar dosti hai". But it doesn't explore it properly just like Kuch Kuch Hota Hai. In fact, it's worse than Kuch Kuch Hota Hai in exploring this concept. That's why people always question whether Rahul truly loved Anjali or Naina truly loved Rohit. When both the movies wanted to tell that Rahul and Naina were always in love with Anjali and Rohit respectively. Tina and Aman were just people in their lives who really impressed them, so much that they thought they were in love with them. But it was just pure infatuation for them.
Naina was NEVER in love with Aman. She just got impressed with him because he solved all her problems. She just got infatuated by him just like her sister Jia. Do you think Jia was really in love with Aman? Nahi na, the same way Naina too was never truly in love with Aman. She was always in love with Rohit. That's why she was easily able to move on from Aman to Rohit just in a few weeks. The problem was, movie never portrayed it properly.
There's a scene in the movie where Aman tries to convince Rohit telling him that Naina just thinks that she's in love with me, but is actually in love with him. That's because he just came in her life all of a sudden and impressed her with his charm, but Rohit always being a friend of Naina, she took him for granted. Audience thought that he's saying all that just to convince Rohit, but it was actually the truth.
I think the movie in the end became all about glorifying and celebrating the greatness of Aman, so much that it overshadowed all other aspects of the film. There's a deleted scene of the movie, which I think was important because it showed Naina realizing her love for Rohit. There's also an alternative diary scene which was also deleted where Aman reads the first few lines written originally by Rohit himself, where we see Rohit confessing his love for Naina. It made more sense rather than audience suddenly seeing Rohit in love with Naina in Kuch toh hua hai song.
The movie actually never explains why and how Aman and Rohit fell in love with Naina. They only show Naina's journey and it's understandable since she's the narrator of the film, so they are showing her perspective, and that may also explain why Aman is so much glorified in the film, because that's how Naina saw him. However, the glorification of Aman brought the film's quality a bit down, though in return it gave SRK a chance to show his exemplary acting skills which again brought it's quality up but for different reasons.
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