-- she DOESN'T like to talk about controversial subjects; and yet -- she WON'T do something that's uncomfortable for her unless you throw down a serious gauntlet; and yet -- she loves me very much.
I suspect the same is true with your wife. She loves you, knows from your letter how serious you are about this, and yet she's chosen to quietly ACT on it, rather than talk about it.
I would go along with it, encourage her on her newfound variation, yet try to keep things LIGHT and HOT HEAVY. I think the mistake I've made in the past is that I want to have some big, heavy, drawn-out conversation about all of this -- in an effort to "understand" her motivations, and perhaps keep doing whatever it was that I did to encourage her behavior in the first place -- but it backfired.
Her "reward," it would seem, might be the lack of a heavy convo if she gives you some of what you want.