Single practitioners can ascend the nine initiations of minor mysteries. But to enter and pass the Major Mysteries, one must be married.
Progress is determined by one's actions. One partner can practice alchemy even if the other doesn't transmute in the sexual act. What matters is that there is cooperation and love, even if the person is "gnostic" or not.
For thirty years I sought God. But when I looked carefully I found that in reality God was the seeker and I the sought. -Bayazid al-Bastami