I truly hope that she didn't 'use' Louis for her own advancement. The timing of the divorce/separation not that long after she finished her studies and secured several 'honorary positions' as a princess could be a red flag - or could be a coincidence.
I think that most definitely she used Louis. I remember when the story first broke that Louis was expecting a child with a young woman who happened to be a soldier along side him, the media depicted her a golddigger. Then she cleverly rehabilitated herself. She studied, learned to carry herself, looked refined and had two good looking boys. This worked and the Grand Duke decided to finally give her the title of princess after early misgivings. Now, the way that she is acting, completely classless and vindictive, I suspect it was all a roost to get that title.