Dil Ka Kya Kasoor

Shalini, the younger sister of wealthy Rajesh Saxena, falls for Arun Kumar after he performs a song she wrote under a pseudonym. She keeps her feelings secret because Arun initially dislikes her, judging her as a spoiled rich girl. The moment of connection comes from his performance of her work, not from any direct confession.

Rajesh meets Arun to assess whether he is suitable for Shalini, only to learn that Arun is an orphan from an underprivileged background living in a hostel. Arun rejects any help or charity, preferring to face the world on his own terms. This encounter establishes a class barrier between the lovers.

Rajesh declares that he will only arrange Shalini's marriage to Arun if Arun attains a social status comparable to theirs. He makes the condition explicit, setting a challenge for Arun to prove his worth. Shalini considers the path she must take to win his respect without pressuring him.

Shalini decides to let Arun earn his place in society rather than forcing a romance. She enlists her friend Madhu to use her money to start a music and stage production company, indirectly nudging Arun toward a singing career. She hopes this path will let Arun become someone both of them can respect.

Shalini begins writing songs for Arun without revealing her identity as Seema. The editor, Mr. Verma, passes the songs to Arun, who believes Seema is a mysterious admirer. The music helps propel Arun's career while Shalini stays anonymous.

Mr. Verma eventually reveals to Arun that the songs attributed to Seema are written by Shalini. He keeps Seema's identity concealed to preserve the intrigue of the anonymous songwriter. Arun is deeply touched by the notion of a hidden muse guiding his success.

Arun's career rises rapidly as Seema's songs bring him fame and wealth. He longs to meet Seema and express his gratitude, unaware of her true identity. Verma continues to guard the anonymity to maintain the mystery around Seema.

Arun and Seema keep in touch through letters, their identities hidden behind the Seema persona. The ongoing correspondence deepens Arun's affection while preserving the secrecy surrounding Seema's true identity. The mystery sustains his motivation and her quiet resolve.

Shalini's brother Rajesh publicly signals his plan to marry Shalini off to Arun once Arun has achieved status, reinforcing the arranged-match dynamic. The announcement raises expectations within the families and sets up the social test for Arun.

Arun learns that he has entered into a marriage with Meena, the principal's daughter. The union is portrayed as a duty to honor the principal's memory, who mentored Arun and left Meena without support after his death. The marriage is practical rather than romantic.

Shalini decides to remain unmarried, but the heartbreak takes a toll on her health. Patches detected in her lungs lead to hospitalization as her condition worsens. Her resolve stands in contrast to the tragedy of her unrequited love.

Mr. Verma informs Arun that Seema—who is actually Shalini—is in the hospital and nearing death. The news drives Arun to rush to her side and confront the truth behind the anonymous songs. The moment marks a turning point in their relationship.

Arun goes to the hospital and discovers that Shalini is Seema. With Meena's encouragement, he symbolically accepts Shalini as his wife Meena. Shalini's condition deteriorates further as the emotional revelation unfolds.

In memory of Shalini, Meena gives birth to a daughter who is named Seema. The name honors the hidden muse who shaped Arun's life, even as Shalini has passed away. The ending ties the generations together through remembrance.