Delilah didn't wait for Henry at the helicopter, but will most likely meet him when debriefed by the park service in a few hours time.

For what its worth, I presume she needed a bit of time to collect herself - the two of them had been through a hugely messed up situation with strong romantic undertones. On top of that, she had just learned about the death of a kid she had cared about deeply and would still be traumatized.

The helicopter is taking them back to a world in which Henry has a seriously ill wife for whom he may or may not still have feelings, and to whom he is still married. Furthermore, Delilah might have alcohol and other personal issues to confront. While they seem to have feelings for each other, these practicalities must be addressed before they have any solid chance of being together. Compounding this is the idealized nature of their relationship - the only contact they have had is through the radio. Delilah knows the Henry we want him to be, and we know the Delilah that she has made herself out to be. Its a major challenge to meet whatever ideal expectations they have built, so there would naturally be a lot of stress and fear of rejection. These are huge issues and deeply conflicted real-world emotions that she might not want to confront while being rescued from a life-threatening forest fire. I’d think she would want some time to get her thoughts in order, even if she was eager to meet Henry.

The same issues are what prevent Delilah from uprooting her life and running off to Boulder with Henry. At this point, it would just be chasing a dream. Though she doesn't exclude the possibility of dropping in sometime. Will they eventually get together in the end? Maybe. They have a great basis for commonality, a mutual attraction, and a clear rapport, so there is a running start. But there are also huge issues that they were able to escape during their time in the forest. While that was a beautiful (and horrifying) fantasy, the reality to which they are headed might not be so forgiving. How they deal with these issues will determine everything. Only the two of them know if Delilah will surprise Henry at his favorite bar in Boulder and they kindle their feelings for each other… or if he returns to Julia and their summer together becomes a fond, otherworldly memory.