She might think you're not good enough, or you're not doing enough to make her feel loved, or wanted, or needed.
You've got to always be there for her, she's not just a tiny slice of your life, she's one of the most important that you (evidently) don't want to lose (right?).
Try something utterly romantic, something that would turn her head, cos right now she's probably going to reject anything of the sort.
But in the end, if she's happier without her, surely you've got to let her be.
Attention: NOTHING on this site may be reproduced in any fashion whatsoever without explicit consent (in writing) of the owner of said material, unless otherwise stated on the page where the content originated. Search engines are free to index and cache our content. Users who post their account names or personal information in their questions have no expectation of privacy beyond that point for anything they disclose. Questions are otherwise considered anonymous to the general public.