Not all of the priests and priestesses had to live in celibacy in our history and even there was a cases of sacral prostituty
also christian priests could have wives in early medieval, a celibacy was ordered later, to keep a Church's fortune only in Church's hand. Elune is the Moon Mother, so one of her aspects must be a deity of feminity (Moon is strong womanly symbol because of it's cyclic nature, most of european lunar deities are goddesses) and fertility. She couldn't require virginity or abstinence of her priestesses (in 'The Witcher' book series was similar situation, the priestesses of Melitele, goddess of fertility, or someone like Triple Goddess, could have sex but for example some of them vowed silence). And this is why Tyrande still can have children with Malfurion, Shandris and Maiev are still 'marriageable' (but I think nobody would as masochist to be in relationship with miss Shadowsong
) and priestesses can show their sexuality.
Also some of the paladins can have progeny. Arthas, as a heir of the Lordaeron's throne, must kept the succession so he couldn't live in celibacy. Tirion Fordring had children as a paladin too. But in this case I think some of the paladins just could take lower ordination to the priesthood (in medieval some of teachers and medics took lower ordinations, because priesthood law was more mild than laic law). The ones who take higher, are a full priests and must keep total abstinence. This is my theory.
And Elune with Malorne... so... if she is a goddess (or Naaru who are also angelic or divine beings) so she can change her physical form. She could make love, conceive and birth a baby with Malorne in form of the great, white doe, or even his birth could look in very another way: he could be even 'sown' as a 'seed' in Emerald Dream and be adopted by Ysera who was a close friend with Malorne. At last Zeus also made love in very forms, for examply as a rain.
So Elune could be a doe, a lightrays, and who knows what ever.