The incident reportedly happened around 10:45 p.m. Friday outside a Circle K on Manchester Expressway.
Kelsey Fish says a man approached her and her boyfriend in the parking lot and demanded her purse.
Fish says she jumped behind her boyfriend, just as the man put the tip of his knife against her boyfriend's chest – forcing her to hand over her wallet.
The man is described as a white man around 30 to 35 years of age and about 5'8. He was wearing a black hoodie and black pants at the time of the robbery.