In the movie Perfume: The Story of a Murderer it's like he liked the first girl's fragrance so much so he just tried to smell her closely, but why does he keep on killing other girls? Was he getting attracted by other girls' fragrance, too? And what did he achieve by killing girls?
The movie uses scent as a symbol of love. The main character was robbed of love at birth when his mother was killed, and therefore spends his entire life searching for love, and hurting other people along the way. Unfortunately, being deprived of his mother's love meant he never learned to love himself, and therefore is incapable of loving anyone else. In the end he finally realizes his tragic condition, leading him to take his own life.
The movie opens with the main character losing his mother immediately after he was born. He then grows up without a scent of his own, but with a relentless nose for other people's scents -- a peculiarity which drives other people away from him. As he ages, his obsession with other people's scents causes him to kill several women in an effort to capture each of their scents as he searches for the perfect scent.
The interpretation is that the main character keeps searching for the perfect scent just like some men keep searching for the perfect woman, or like addicts keep searching for the escape of getting high. Each time the main character is able to capture a woman's scent, he finds himself unsatisfied and kills the woman -- just like real-life "Don Juans" are unable to find long-term happiness in a committed relationship, or like real-life addicts are unable to avoid the inevitability of coming down. Each woman the main character kills represents a sexual conquest that ends in the woman's heartbreak, or a bender that ends in the inevitable painful hangover.
Overall, the main character is driven by his fractured childhood relationship with his mother, which left him with no scent of his own -- just like real-life Don Juans and other addicts are thought to be driven by "mommy issues" that leave them unable to love themselves. The main character's suicide at the end symbolizes the two most common outcomes for the main character's real-life counterparts: either self-destruction or a life-saving relinquishment of their self-destructive ways.