The girl I love has a boyfrend but her and i are long distance and he is there. What can I do to win her over?

There is this girl I am in love with. I guess you can call her an ex, I don't know if she ever considered us official. It was a long distance relationship. I guess if it was official, it's technically been considered over for about 6 months. But she still didn't see other people. I wouldn't even dream of seeing anyone else either, not even now. Lately, we haven't talked as much, even though up until a week or so ago, we were still saying I love you to each other and such. Well, I've been worried about our steadily digressing relationship (by that I mean our connection, not so much an actual relationship). I've been trying everything and anything to make it work. I've tried being a part of as much of her time as possible, but it backfired. So I laid off a bit, tried not being so clingy towards her. But that seems to not be working either. I fear she now has a boyfriend and he lives in her town, where as I live 12 hours away. I need advice on how to win her back. I love her. This girl is the reason I wake up in the morning, the only thing that matters to me in life. Nothing makes me happy when she's not involved. I have cried myself to sleep every night for the past 6 months. The answers I am seeking are how to improve the situation, not looking for some jerk to tell me to just move on. Like I said, I can't move on, she's my life. To tell me to move on would be the same effect to me as telling me to go kill myself and that's the honest to God's truth. So please, I really need advice.