For best resuslts have her to pick up someone in a hotel bar but have her invite someone to your home. You might watch her with others but you will have the best pussy ever after she fucks someone else. Enjoy your meal.
A good time will be had by all after you lick and clean her pussy and asshole after used by another man. U will love your wife more and more after u lick her clean.
Can't really make her a slut, she is or isn't. Many women repress those desires and it is up to the right person(s) to bring out that inner slut. Buy her classy but sexy outfits to wear when you go out. Men will notice and, if you give the opportunity, they will hit on her. Enough of that will help bring out her desires if they are there. She looks amazing by the way!