An Indonesian couple in Kuala Lipis suffered acid burns after the man accused his girlfriend of being unfaithful to him, reported Harian Metro.
The 40-year-old man, who had been dating the 49-year-old single mother for about a month, had proposed to her, but she gave excuses to delay the wedding.
After spending thousands of ringgit to win her heart, a friend finally told him that she was not "wife material" as she had many boyfriends.
Enraged, the man took a bus from his home in Seremban to their shared home in Kuala Lipis three days ago, arriving there at about 1am and confronted the woman.
The woman, a canteen worker at a construction site, dismissed the accusation as mere rumours created to break up their relationship.
Not convinced, the man took a bottle of acid and tried to force the corrosive liquid down the woman's throat.
However, the woman managed to push his hand aside, causing the acid to spill onto her face and back as well as the man's stomach, legs and arms.
The man fled the scene, but was arrested when he got off a bus at Raub at about 7.50am the same day.
Bystanders sent the woman to the Kuala Lipis Hospital, from where she was transferred to the Sultan Haji Ahmad Shah Hospital in Temerloh, where she is in a coma.