My fiancée wants to watch me sleep with another woman.

I’m 22M My fiancé 20F has always been attracted to other women but never experienced one. It started out as she wanted to have a threesome with me and another woman before we got married. We found a couple women but there was always problems that made her shut it down. They seemed to be more into me or they wanted to be in a love triangle so on and so forth. Well it graduated to her wanting me to have sex with her and another woman at the same time. Well it always seemed to be the same thing find someone we talk flirty maybe even dirty talk. Then she starts to feel insecure. Well now it’s all the way to she just wants to watch. When she said this to me I was a little in shock. Part of her shutting it down was she didn’t like how the other women would degrade her and then she comes out and say some of the stuff they would say would really turn her on. But other things they would say would make her feel really insecure. Is there any women out there who have done this or went through what’s she’s thinking that could help explain this to me. I kinda have whiplash from the back and forth over the last couple years. I can’t decide if this is a test before we get married or not. She seems pretty adamant on it even when I try to shut it down.