Gomory teaches them secret techniques of love in exchange for the summoner's riches. If the summoner happens to fall in love with Gomory, she tends to take advantage of their money....it's questionable that she truly provides happiness.
See Impudent Gomory.
In demonology, Gremory (aka Gamory, Gemory, or Gomory) is a strong Duke of Hell that governs twenty-six legions of demons. He tells all things past, present and future, about hidden treasures, and procures the love of women, young and old, but especially maidens.
He is depicted as appearing in the form of a beautiful woman with the crown of a duchess tied around his waist, and riding a camel.