Girl went from hot to super cold. What happened?

[nothing003]

There was this girl that I was flirting with and getting good vibes from, we went out in a group, and all the while I got nothing but positive feedback. She was freaking staring at me for a while, at one point she pulled me in and said "I like you," and we made out. I pretty much assumed a hookup was a given. This whole group was staying at a coliving place and I didn't know exactly what to do to separate me and her from the rest of the group. After we got back home--again we were all in the same place--I suggested we all sit and talk for a while and I was going to try to figure it out. Instead, she announced she was going inside, and instead of chasing her or arguing with her, I just said "goodnight." The next day, she would barely say a word to me--it was absolutely night and day. The situation appears totally dead in the water now. I'm struggling to figure out what happened. I think there are two possibilities: 1) she was mad because I didn't make the hookup happen. Should I have chased her when she left? It's my usual policy to never do it. 2) She just decided at some point that maybe she'd rather have me as an orbiter, could have been something subtle that I did or she just changed her mind about me, I can accept that that's possible. But her signals certainly pointed the other direction until the end of the night. And now the situation is ice-cold.

Help me figure out what happened here!

 

[OldGuy]

She may have been seting up the lay by going inside. You should have followed her in and seen where it went. (Women will casually set it up with plausible deniabilty.)