HELP!!!! SOS!!!! =(

I dunno what to do. I mean....... What do you do when you love someone and they just keep lying to you? They always say that they're telling you everything, but then they forget that they lied and then the truth comes out. Like rain from the sky, it hits you. Right inbetween the eyes.
You let it go everytime but it just keeps happening. And everytime, you die a little bit inside. Everyone does. But I can tell you one thing, pretty soon there isn't going to be anything left to kill.
let me put it in story form................................:
theres a guy and a girl. they meet at a concert and get to be really close. girl & guy date for a few weeks before boy breaks it off because he "hardly ever gets to see her". She cries and it breaks her heart. they don't talk for a while, a month or more. Girl tries to put it behind her and stats tlaking to someone else who likes her and vice versa. Then boy comes back and wants to be friends. so they are friends and talk everyday. Then girl finds out that there is another girl in his life: a girlfriend. she pretends not to care and they hangout at her volleyball match. Guy kisses girl and tells her that he broke up with the other girl a few days ago. and for a while, everything is good.
then the next day at school girl's other guy friend kisses her. she's confused but decides to trust the boy one more time. she stay away from the boy who kissed her. right before christmas, other boythe boy she let go scares her. so the girl says nothing....just cries. then over break girl has to have surgery, nothing major but she's still scared. so she calls the boy she went back to and he hangs up the phone on her. because theres another other girl and now Girl has been forgotten again. so girl has surgery and heals. then one day she just wants answers and decides to call boy. Boy nearly overdosed and is sick. nobody but girl knows and she tells him what to do to get better.
Girl saved the boys life. she finds out that his girlfriend dumped him and he tried to feel nothing. she helps him threw it and forgets that she was ever angry with him. they start talking again like no time has passed. then they grow apart for a while. girl found someone new who didn't make her hurt inside and she got close with new boy. it doesn't work out and girl feels stupid and alone so she calls Boy for help. But instead of helping her feel better boy calls her tainted and hangs up on her again. poor girl is on her own again. So they don't talk for a while. and she moves on.
but boy wants to make it all right, he calls her all the time and instead of being a good friend, guilt trips her about it and makes her cry. but girl keeps it all inside, thinkin gits her fault. so boy asks her to prom and she agrees to go with him. hen a few weeks later he calls her with news that he's got a date to prom. girl said nothing and listened as he tells her how he's going with a girl who asked him from his school. he calls her all the time and its almost like their friends again. like nothing ever changed.
but then boy calls girl one day after school and asks her if she'll go to prom with him. he tells her how he really wanted to go with her and how sorry he is that he fogot about her. girl accepts it as her fault and agrees to go. they make plans and girl gets a dress. their parents meet and its all good like it's supposed to be. then girl finds out that when boy was guilt tripping her about her other guy that he had a girl friend. girl lets it go cause it's all in th past. and the next time they fight he blames her for his "iokesmng" problem that girl didn't kow about.
girl blocks his call until he says he's sorry for hurting her. and she forgives him again. prom rolls around till its only a few days away. they talk about plans and stuff. they've been dating for almost 3 weeks now. they girl finds out that when guy was telling her he loved her when he was going to prom with "ther girl" they were dating. now girl doesn't know what to do. everytime she tried to move on, he came back and wanted her again. but all the times he said "I LOVE YOU" there was always someone else. guy makes up the rule and girl follows them. they don't apply to him.
So girl doesn't know what to do know. she wonders if she;' given him too many chances and if she should walk away after prom. maybe even before then. this poor girl is tired of being in the wrong when all she does is love him.
What should she do??????