What are the reasons for why this girl stopped liking me? (females preferred)?

im going to give u all the details i can, and if u can give me a good answer itll be appreciated. well me and this girl talked and stuff for like 2 months, feb-april (yes i know it aint a long time i aint sayin i love her n ****, i caught feelings though) and then she one day she randomly stops replying, doesn't really wanna chill, etc. then we stop talking and like 2 days later i find out she's going out with this boy she went out with for like a year before. so then they only lasted a like 2-3 weeks, lol. so then i tried to talk to her again and she says no because i "talk to too many girls" .. like i talked to alot before me and her started talking, but i didnt talk to any while we were talkin... wtf. so then i chased her for like a few weeks, now it's like early June, so now we talk for like a week, and one day she pisses me off (im kindof an asshole here) because i go to chill with her and i dont have a phone and she didnt show up so when i talked to her next i went off kindof, then she tells me she had to do stuff with her mom. but anyways she says she still likes me, but i was so mad i just started talking to other girls and basically said **** her. now, apparently she don't like me no more and im just playin girls now... partly because i dont want to deal with **** like that again, but then she never chased after me? wouldnt you think if she liked me she would of cased me? and now she doesnt like me like wtf? how do you go from liking someone a lot to not at all just like that?