Why are girls like this?

Iv been speaking to a girl non stop for about 5 days straight literally constantly all day until we sleep. We had a date planned for Saturday and we kept talking about it and having a laugh, she even told me she couldn’t wait to see me, Then tonight she tells me next year she’s moving in with 3 guys for her uni house (they all have girlfriends) and I made the joke about her getting with the guys. Then she completely switched and just became really dry and told me that I sound like I don’t trust her and she thinks it’s going to be a problem that she has guy friends! Then she told me she no longer wants to go on a date. I’m so upset and confused! Why did she switch up like this? Iv never had a girl change like that. Now im going to be constantly thinking all the girls I talk to in the future are going to do this. Did I do something wrong or did I dodge a bullet?