I think this is more complicated as essentially you're flying in a name you've never held, not that that WAS your name and you've legally changed it but it's in your old legal name. The second situation is much more common than the first and makes more sense than the first, where essentially the ticket is just booked in the wrong name.
If you can't change your ticket now, you should be able to if you call them, especially if she booked it directly and not through orbitz or something, then you should turn up at the airport early, and try and change your name on your ticket at the airline desk (not the check in desk) likely they will change it for you (they totally CAN) but it may take ages.
Have you called the airline yet?