The 24 hour engagement.

Sounds like her first instinct, of not going, was the right one. She probably was drawn in by the romance of the trip and the proposal, and after you guys got back realized it was a mistake.

Protip (more pro than I wish I was): never propose during or immediately after a "rough patch". If your girl says she needs time, give her time and don't try to step up the romance or the relationship until things are good and have been good for some time. A lot of people try to "fix" their relationship by getting married or having a kid, and this is a terrible idea... never never do that!

That said, you may have to let this relationship go. Don't push it. Give her the time and space she needs... if she comes back around, that's great. If not, realize that it wasn't meant to be.

I can only speak for myself, but nothing sends me running faster than relationship pressure when I need space... something to keep in mind, perhaps, for future reference.