I think the DA and city of Duluth are going after her now because they got many complaints after the police chiefs initial remarks that they weren't going to charge her with anything.
Which is the medias fault really. Most of these cases don't even make the local paper let alone national media. I suspect there are a lot of people who deep down believe she should be punished for leaving her fiance at the altar. Perhaps she should, it isn't a nice thing to do, unfortunately for them, it isn't illegal.