Their car collided with a semi-truck just before 5 a.m. Saturday near 18th Street when the female passenger tried to grab the wheel and cut it too hard.
Police say the car veered across all of the lanes and ended up in front of the semi.
Both the 24-year-old driver and 25-year-old passenger had to be cut out of the vehicle.
The driver suffered minor injuries, while his girlfriend is listed in critical condition.
No one else was hurt in the crash.