I really would love to tell you to keep trying, but this isn't about you. It's about her. Like
>>2 said, she wasn't by your side for your worst, so why should she deserve to be with you during your best? This is going to sound ridiculous, but hear me out. It's almost like being a sports fan. It's very easy to cheer for a team when they are winning, becoming champions, etc. But it takes a TRUE fan to cheer for a team when they lose, are on a losing streak, etc. To be frank, she wasn't cheering for you on your losing streak, and instead started cheering for another team. I'm sorry if I'm sounding harsh, but that is what I think of the situation. I've been in love with a few girls that just brushed me off as well. It sucks. And even though it's hard, try to find someone else. Don't cut all ties with her, but you need someone who will support you through the best and worst of times. Hope this helps!