How to Live with a Messy person!?

I live with someone who I really care for who doesn't understand the meaning of organization or tidiness. I mean I've done everything from straightening things behind them to leaving hints here and there but it never seems to work. Example, I purchased her a $125 hair straightener, now to me that's expensive, but I thought to myself hey she's the love of my life why not? Next thing I know I see it hanging around cord stretched out to the floor and thrown like I paid .25 for. I am starting to reminisce my bachelor days when everything was neat and clean and it was always easy to find something. Now, I live with a woman who would make Oscar the Grouch look like Martha Stewart. What can I do and what would you do?