<human>: So I met her at a group I'm in that meets once a month. We seemed to really get along well. We started talking outside of the group, we had some video chats, and we went out on what I was sure at the time was a date. (We got milkshakes and went for a walk.)

This Monday our group took a trip and she was acting normal at first, but throughout the day she started acting less and less interested. I backed off thinking I was being annoying. By the end of the day she left without saying goodbye. 

Now she takes a lot longer to respond to my messages and when she does the responses sometimes seem pretty curt. It blows my mind though, because everything seemed like it was going great! She even said that she wanted to ask me to prom (too late :( ). 

I just don't get it. Sorry if this seems too much like a high school puppy love problem, but it's just been bugging me. I've never had a girlfriend so getting this close and it going wrong is frustrating.

Summarize the given text in a few sentences.
<bot>: things were going great, but now, seemingly without reason, they have gone downhill and I don't know what to do.