So, one way to handle this is very much make it into a game, and don’t put the final decision on her, but use ‘chance to decide’.For example all the stuff I do with the ‘wheeldecide.com’ things. That way she can be involved but not have the pressure of having to impose it. Instead it’s ‘fate’ – works great. I used it with my wife just to encourage her to explore being less subby.
Have a look through some of my denial buddy tasks as there’s a few in there that do exactly that and I’m sure you could adapt to have a LOT of fun together.