A teenage girl is fighting for her life after two cousins allegedly got in a lover’s quarrel over her outside a Corona supermarket today, authorities said.

The dispute broke out at 9:10 a.m. outside the Fine Fare Supermarket on 37th Avenue and 109th Street in Queens, cops said.

“One was jealous of the other because of the girl,” said Melida Diaz, 62, co-owner of the supermarket.

Diaz, who watched the store’s security tape, said one man stabbed the other in the arm and that the 17-year-old victim then fled into the store.

The stabber ran in after her and knifed her multiple times in the chest, sources said. He has a baby with the victim and was jealous because of her relationship with his cousin, other sources added.

A security guard who witnessed the dispute called the police.

The 20-year-old cousins both had non-life-threatening injuries.

All three were rushed to Elmhurst Hospital, where the girl is in critical condition, police said.