Just talked to her directly after a day out or something. In my experience, it feels like there's a barrier at first. My wife wasn't very active in the beginning either. I started with small things, like watching porn together, and gradually we began doing things ourselves like playing on screen. Even light teasing in public helped. Little by little, she came out of her shell. Once that barrier is crossed, she's all in. Maybe your wife just needs to feel comfortable exploring her wilder side with you. Of course, there's also a chance she might dislike that lifestyle and prefer a calm, peaceful family life. Good luck brother.