I understand that you must feel very confused about what this girl really thinks about you. You've had small flings before, last week she told you that she has feelings for you too and now she is suddently dating another guy. It is not necessarily a fact though that she has friendzoned you. It seems to me that she is unsure about her feelings, that she is a bit confused and haven't quite made up her mind about what she really wants at this point in her life. I believe the only thing you can do is to talk to her and ask her to be honest with you. Did she mean what she said about having feelings for you? Has she changed her mind? Tell her that you feel a bit frustrated about not knowing what she really feels and ask her to tell the truth, whatever it may be. Maybe she can't give you the answer you want right now, if she doesn't know herself what she wants. But at least it might make her realize that it's a bit unfair to say she has feelings for you and the suddenly move on to another guy without explaining anything. You deserve to know what's going on. Good luck, I hope this helps.
