Girl's Behavior

My crush is suddenly becoming cold towards me, what should I do?

Well, my crush and me started to get really close to each other, for some time now. We started talking about a week before spring break she told me stuff not many people knew about her supposing she trusted me and I did to her. One day we had a movie night and we cuddled, stroke her hair and holded hands there. A lot of her friends the next day asked me if I was into her and I said yes, they said that was super cute. Well vacations started and she went on vacation and I did as well, so we kept contact via Text Msgs, I was usually the one starting the conversations. That was for two weeks. Now we are back to school and the first day of school she was super nice to me and we had these "stares" she blushed and I smiled. We then texted with each other for the whole night. The next day she started acting cold towards me, no real reason what so ever she started flirting with other guys and well she distanced her from me.
So now today the same happened but worse, I haven't caught her staring at me with usually happened, she used to always be interested in my conversations and always smile/laugh at me. I tried to text her these two days and she reacted really cold. I don't know whats going on really, I haven't told her yet I like her or asked or on a date, I was planning on doing that this week. I don't know what to get from this situation, does she want me to take the next step ASAP? Have I lingered/lasted too long? Has she lost interest in me? Her best "male" friend told me before this all coldiness thing happened that there is something I don't know yet that he won't tell me because I'd rather hear it from her, and he seemed quite positive about it since he is my friend as well. I know I might be overreacting but I really care a lot about this person. Any tips are always welcome
My crush is suddenly becoming cold towards me, what should I do?
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