Hey there...
That's a tough situation cos I know you really love her but looking in, the truth is that she's not putting in what 2 ppl need to do to make something work. A relationsihp works two ways right? You're giving a lot and you can't quite say she totally is. I also know you might think she's 'the one' for you no matter how she acts now you love her too much to see that she may not be...The thing is, you never really know if someone is the right presonf or you..And somtimes it takes 1 gf, or a couple to realize what a relationship means to you and all that sort of thing...But the important thing is that the two of you feel the same way...You are 18 and though it may seem hard to move on, it might be the best thing to do at the moment. You've done a lot of the chasing, sometimes when you give yourself a breather and get your mind off her by keeping yourself occupied, she'll realize in time what she lost! Don't give up hope either...some couples sometimes get back together too you know? I definitely agree with you that she should try changing her habits cos its undersetable why you felt she may not have been completely trustworthy...But in the mean time, go out with your friends, keep occupied, kay?