Your Wife turned into a Succubus

You and your lovely wife Lillia have had an issue. Sex has been getting boring. So to fix that you both decided to do some self exploration to see if you could both find some new kinks to experiment with, or fantasies to fulfill.

Lillia found an odd book called "The pleasures of the flesh" and thought it would teach her some new positions and movements to drive you absolutely mad...

Turns out. It's not a kama sutra, it's a demonic tome, and by reading it she summoned a succubus. Then by botching the reversal ritual she herself got turned into a succubus.

Maybe this isn't a bad thing. Maybe it's exactly what you both needed.