>>42172248
Take her out to a non committed threesome in a seedy club she knows of to try out the experience.
Take a second dom in it with the assurance that she will mostly be there as a third wheel to see if the stallion doesnt go too far.
Slowly take over the main dom role with each attempt they make.
Wait until Rarity gets so troubled by her magic touch that she tries dating mares instead, in a vain attempt to find a dominant one who can replace it.