Is this something you’re comfortable with trying? For me I’m usually of the mindset that if I go to try something I can always stop if I hate it. Maybe go at this with an open mind and try it once. If it’s not doable for you or if it’s not something you can do often tell her this.

It’s not a typical fetish or one I’ve ever heard of. Maybe see if she would see a sex therapist to uncover why she wants this? It might help her expand her horizons so she could try other fetishes you might be into.

Ultimately if this isn’t for you and she can’t give it up then you are just not sexually compatible. Don’t do anything you aren’t comfortable with doing. Although this situation is so different that it’s funny, it’s still a reality for you right now. It’s still your body and you choose what you do and don’t want.