The deceased identified as Sunil was in a relationship with his colleague for the last 12 years but she stopped talking to him, police said.
The girl's family alleged that Sunil was not respectful towards her and recently they had found a guy for her to get married which agitated Sunil, they said.
On Saturday, he came to the girl's home carrying a poisonous substance in his pocket. When the girl's family tried to intervene, he said that he wanted to speak only to their daughter.
The man was rushed to a hospital where he succumbed during treatment yesterday, they said.
The girl claimed that she wanted to break up with Sunil but was scared of his violent behaviour.