[morethanpretty]

disenchanted-
I think you didn't do anything wrong on purpose. I agree with daff that you were probably getting mixed signals. Here's the thing tho, if your girl had agreed to go away for the weekend based on your promise of "no pressure," then she expected it to be "no pressure." When she told you "surprise me" she obviously didn't mean for you to do so that particular weekend. Or at least that seems obvious to me. You said the week leading up to the weekend was great, ya'll were having a marvelous time with each other. Probably due to the fact that you had promised that there would be "no pressure" that weekend. She felt secure that she wouldn't have to be answering such a heavy question and that allowed ya'll to relax and get along better. I'm saying all of this because although I know you listened to your heart, I don't believe you were truly listening to her. "Surprise me" does not mean "surprise me on the weekend we've already decided will not be the weekend."
If you do get back with her, leave all this behind you. When ya'll talk it out, take the blame. That might seem hard, because you seem to want to find fault with what she said. Its not what she said, but how you interpreted what she said. So don't bring it up. Say you made a mistake, you misunderstood and that you will try better to understand her wants. I don't think you have a chance to truly mend things otherwise.
I'm going off of what I know as a woman, and how I would feel about the situation. I know that I would kick you out the door so fast if you started blaming me.