The victim identified as Vineet was rushed to Hedgewar Hospital where he was admitted with serious burn injuries on his face and later referred to Guru Tegh Bahadur Hospital, police said.
The woman has been arrested and has been identified as Aarti Dikshit, they said. The incident took place in Anand Vihar around 12.30 PM, when the couple had gone for a movie to Cross River Mall where they decided to return home after they did not get tickets.
"Later, after walking out, Aarti took out a bottle containing acid from her purse and threw it straight at Vineet's face," a senior police official said.
The incident happened after Vineet said that he could not get married to her as his parents had objected to the match.
The two knew each other for the past five years. Aarti, a resident of Yamuna Vihar, is looking for a job, while Vineet, a resident of Maujpur, is a sculptor and works with his father in the business of selling idols.