Why is she such a %&$^&??!?!?

So theres this girl i kind of like, and i think she has an amazing smile, and shes always messing around with me by playfully hitting me or saying insults. its quite annoying but im to nice to say anything. So anyways i told my friend that i think this girl has an amazing smile, and he ends up telling her and he said she ended up saying "ewww gross" but wasnt serious about it. So when i saw her walking with her friend, in the hallway they were talking and she saw me and she smiled and immediately came up to me (ditching her friends in the crowd so it was just me and her walking alone) and said "i heard what your friend said about me you weirdo hahaha" and i was like what do you mean, she said you know what you said about my smile.. and i was like i gave you a compliment and you call me weird.. she got really close to my face like it was way to close. she then laughed and i have my headphones in and she yanked them out and called me a "fat" mind you im not fat, im more of a football kind of built though. and i walked with her to her cl, and she walked way to close for my comfort to where id push her away and she still come back to walk close to me, she basically gave me no room to move, why was she so mean about me saying she has a nice smile?