My Girlfriend Charges Me Rent But I Only Sleep Over 5 Nights a Week

My girlfriend Diana owns her condo. I'm there basically every night — I keep clothes there, cook dinner half the week, and do chores. She recently asked me to pay $800/month in rent. I was shocked. I don't have a key, I still maintain my own apartment (which I'm barely at), and she says if I want to live there I need to commit financially. I offered $300 for utilities and groceries. She said that's insulting and if I can't pay real rent I need to limit my visits to 3 nights a week. I feel like she's commodifying our relationship. She says she's not running a free hotel. I told her I'd start staying at my own place more. Now she's hurt that I "don't want to be there." I genuinely can't win.