Speaking from the side of someone who has hid toys in prior relationships from my partner it was because I wasn’t happy sexually and maybe felt like I wanted fulfillment and couldnt seem to have conversations about that. They were not able to comply and sent signals of if I wasnt happy it was their fault which was not 100% the problem. I needed my own private time for intimacy for my own good. Without pressure of emotionally charged issues. I cannot really know her reasons just why I had done it before. I hope you might be able to give her space and wait. She has reasons and very well could have nothing to do with you. The relationship I am in now lets me be me so freely I dont feel the need to hide anything anymore.