BlameAnesthesia posted...I don't understand the girlfriend's injuries. She "needs attention", but it sounds more internal bleeding or head injury as there is no gross hemorrhage. As a bystander, there is nothing you can do more for that until EMS arrives and arranges for transport to a trauma center anyway.
As for the lover, a bystander can apply pressure to help control some of the bleeding. The rate limiting step here is time to a trauma center.
Also if you go by mass casualty protocols, you triage green-yellow-red-black, with black meaning injuries so severe death is imminent and resources ought to be allocated to severe injuries that does confer chance for survival (i.e. red). Since there is nothing a bystander can do for the girlfriend until EMS arrives, the other inspanidual should receive the attention. (Not that two people in a collision is a "mass casualty" but this scenario seems to be implying limited resources so it's quasi-related).
Unless you change the scenario to both of them hemorrhaging, then really it comes back down "will they survive the trip to the hospital for more definitive treatment?" Attention goes to the most survivable injury, not necessarily the most severe (e.g., a ruptured aorta from a high speed motor vehicle collision is like >90% fatal. They aren't making it to the hospital.)
This. OP didn't specify the car being on fire or in danger of exploding, so there's nothing you can do that will help the girlfriend. Leave her where she is, help the other guy.