One of the duo claims to be the husband of the student and the other person his sister, but the student has denied marrying him.
Acting Proctor Md Rashed Talukder told bdnews24.com Professor Sajedul Karim of mathematics department saw the man, identified as former Chittagong University student Kawsar Ahmed, slapping the victim on the campus on Friday afternoon.
A woman, identified as Chittagong University student Faiza Rahman, who was standing beside Kawsar, asked the teacher to mind his own business when he wanted to know what was going on, Talukder said.
The victim told the teacher she had no relationship with Kawsar.
Her friends said she had a love affair with him for three years but recently they broke up.
Jalalabad Police Station OC Akhtar Hossain said the victim started a case against Kawsar and Faiza over abduction attempt later in the day.