Think of this from her perspective - She thinks of you as a friend. She has just started a new relationship. Now, instead of being happy for her as a friend normally is, you tell her you like her. This probably will just confuse her and possibly anger her at this point.
Frankly, if she has the same feelings for you that you do for her, she has pushed them down enough to the point where she wants to date someone else. I would suggest staying her friend and riding it out.
Good luck.
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