I (18M) told my gf (18F) that I might like to try something new in bed. We tried and it turned out I didn’t like it but now shes mad at me and I dont know why. Can someone help me understand her point of view and help me figure out what else to say?

So a few months ago my girlfriend was asking me about things I had thought about in bed and asked me what I thought I might like. I said I thought the idea of her lightly choking me sounded kind of attractive and she said it was weird but that was it. Later that day she tried it during sex and I wasn’t feeling it so I told her and that I just wanted to do it normally and moved her hand away. She was noticeably upset after that and said, “I asked her to,” and that she didn’t really want to but only did it for me. (To be clear I never asked her to, I just told her that I thought I might like it) I told her the idea was better in my head and I thought wrong and it didn’t have anything to do with her, choking just wasn’t my thing. It thought it was okay after that but now she brought it up around 4 months later and is saying the same thing. Can anyone give me advice on what to do/say and help me see it from her point of view? I don’t really understand why she is upset.