What should i do about my girlfriend?

Im a and im 16.... I've been dating this girl i met for about 2 months and 12 days and i feel as if things have changed. At the beginning of our relationship she was very sweet and always re ured me that i was the one she loved. (re urance is something i absolutely need in a monogamous relationship) But lately when she talks to me she does it like im her friend and when ive talked to her about it she says that shes a stud and its weird to show her feelings but that she does love me. (im a fem) Which is what i would believe if it wasn't for her constantly starting fights with me. for example the other night she called and said she was cheating on me. I was so upset i started crying said bye and hung up the phone. She then texted me furious and said that she was kidding and now she was mad at me for hanging up. Ive asked her if she wants to be with me and she said ofcourse and that she wants to marry me but if thats how she feels why does she make things so hard for me . . . I need to feel loved. . . and im not sure shes doing it for me anymore. any suggestions?