My wife is curious about starting an open marriage

A few days ago my wife dropped the bomb on me that she’s very curious about an open marriage. She’s unsure if she wants to try but finds it intriguing. She’s been subtlety/playfully bringing it up 3-4 times a week for the last few weeks. She has also stated that she only wants it to be open for her, not for me. I told her if we were to do this then that would absolutely not be an option. After some prying she admitted that she thinks the idea of me being super jealous and what not from her seeing another guy(s) is a massive turn on for her. I personally feel like opening a marriage could only lead to disaster. Wish I could provide more info regarding the backstory but this is pretty out of the blue for her. Any advice/insights would be welcome, thank you