Does this seem like FA behavior?

I have been seeing this girl at school for the last month. We got set up together but we hit it off and hung out a ton. Over the last month, we would see each other multiple times a week and slept over at each others places multiple times. She expressed concern about me still being with my ex. I told her if I ever got into something serious with someone, I would not hesitate to cut my ex off.

A few days before winter break, she invited me to her place. We cuddled and hung out like nothing was wrong, and then all of the sudden she started acting strange. I said I was going to go and she asked me to say and just lay with her. Eventually, she started crying and said she does not think we should talk over break because of my ex. She said she could not handle thinking about me hangout out with my ex while texting her. I asked her what she would want to do if I came back from break and my ex was out of the scene, and she said she would like to continue things. I accepted that, and left. Later, I texted her basically saying I would cut off my ex and I wanted to continue things. She responded, saying she really likes me and if it is clear that my ex is out of the picture, then she also would like to continue. We then went our separate ways for break.

A day into break, I met with my ex and basically cut her off. A day later, I texted the girl I have been seeing to let her know. She responded 24 hours later basically just saying "thanks for letting me know" and then asked a few clarifying questions. We then talked the whole next day. The conversation was great. Lots of flirting, joking, everything you would imagine between two people who like each other. I ended up going out that night to a bar with a few of my close friends, but I was texting her the entire time. Then on Thanksgiving, she totally stopped responding. I texted her again 36 hours later and she responded. She asked me how the bar was, and when I responded, she accused me of lying to her about my ex and hanging out with her at the bar. I absolutely did not lie, I truly did cut off my ex and have not seen her since. I told her this and then told her I would like to talk about it if she would like that, and she never responded. It has been 4 days since then.

I dont really know what happened. It seems like it was going great and then she just got scared. Part of me thinks she just does not want to deal with an emotional situation while we are both on break, but I am so confused.