one thing. monstergirls get man´s spirit energy through sex but can human man gave monstergirl´s their energy without sex? if a monstergirl loves a man so much that she will only have sex with him and with no other than that is good thing when she needed more energy as her husband can give her. a vampire can get blood from man without byting them maybe a man can feeding a monstergirl with energy when he is willing to gave her someone.
no she grant not wishes but monstergirls can fulfill wishes that humans most desire. 1. eternal youth without ageing. 2. big riches. 3. active sexlife.