My roommate that I have a crush on is angry to me for some reason, I dont know how to approach her

I live with a female flatmate. Over the last year we’ve gotten pretty close. We talk a lot at home, cook together, eat together, watch movies, and sometimes study together. At some point I developed a crush on her, but I always assumed she didn’t feel the same, so I never crossed any boundaries and treated her as just a friend.

She’s very friendly with me and opens up about personal stuff, family issues, stress, etc., and has said she trusts me. She’s also suggested activities like movie nights, cooking together, studying at the library, and even invited me on a Christmas trip with another friend.

But we had an argument on the trip. We were talking normally but she suddenly got mad about something that I said. I have no idea what I did wrong. I tried to talk with her about it but she didnt want to. We didnt talk in the rest of the trip. When we arrived back to out house, I asked if she is still angry, and she said "dont worry it will go away eventually". I asked her again why she got angry and then she said "for some reason, i didnt like what you said" but she didnt make any clear explanation.

Since then, she’s been distant. After the trip she went back to her home country for a couple of weeks. I sent her a simple “have a nice trip, take care” text, and she didn’t reply. She’s also stopped viewing my Instagram stories, even though she’s clearly active on the app. So I assume that she is still angry.

She will come back home soon, and I dont know how to apporach her. Should I try to talk about the conflict again, or try to talk normally as if nothing happened, like "how are you, how was the holiday"? Again, I really dont know why she got angry in the first place, and then why she is still angry even though two weeks has passed.