Dave, I think you should just talk with her about this.
Ask her if the 2x per week is going to consist of the types of encounters you have been having--with her bringing no desire, nor trying to tap into it while you are ML. Her desire is not an essential component; we can all ML to our partners with little desire now and then and not fret about it. But if it is becoming a regular thing, then I think you are compelled to call her on it.
Right now, I am at a loss for words on how to best say this, while remaining compassionate. I will think on it and get back with you.
She also might be testing you..or trying to get this "experiment" to go away by being available but not bringing anything to the table, so to speak. If you give up, then you have proved her right..that this is not that important to you and it was just your latest little adventure. So stick with it--there is so much to gain!
And maybe it is time to revisit what kinds of things get her going--have you ever asked her, and has she been able to give you a satisfying answer?
I think you should ask her the "why" questions; I could see that they were very thought provoking to my H, if nothing else. Although his response as to why I would want to ML to him was pretty predictable: "There is no reason." Very telling!
Hang in there and get some nourishment and rest and then let us all know how the talk goes.
