The one you call the lover is actually the Beloved – Rumi

The Sufis imagine Allah (God) as an intimate Friend, not a distant Lord of the Universe. He is their Beloved with whom they share a passionate, sacred love affair.

By imagining Allah in this way the devotee is able to enjoy a personal relationship with the ineffable One.

…

Sufi poets are aware that, in reality, the Beloved with whom they are enjoying a divine romance is their own deeper Self. The love affair between the devotee and the Beloved is the One become two in order to love itself.

Rumi sings to Allah:

You – the soul free from “me” and “you.”
You – the essence in every man and woman.
When the sexes become one You are that union.
You created this business of “me” and “you.”
so that You could play the game of wooing Yourself

Source: The Heart of Islam p. 82-83 by Timothy Freke