[May be a bit of a trigger warning. Maybe not. Lore is lore, I guess.]

"Oh, Goddess! Yes! Thank you!"
-
It would appear these two have figured out the true reason for their meeting and why the Goddess had blessed her precious Keeper with a woman's anatomy. After some months spent visiting the temple, our young paladin found himself enamored by the little demon. He was subtle with his recent intentions, but still made his attractions known. The Keeper, having never experienced the the intimate touch of another, and finally willing to somewhat accept his own emotions, reluctantly catered to the human's advances. He learned of two truths on that fateful day. The Goddess had, in fact, given him two blessings: a womb, and the perfect mate to fill it...
-
Now, onto the depressing part as to why he doesn't exactly physically fit his personal identity anymore...

The Keeper unfortunately had his manhood stripped from him by his own mother when he was a child simply because he cried once. Since then, he has wholeheartedly hated his own kind and despises his own image. One very early morning, just before daybreak, The demon was wandering the forest aimlessly when he stumbled upon a crumbling and weathered statue depicting a beautiful human woman dressed in loose silks, holding a sword up to the heavens in one hand, and carrying a bouquet of flowers in the other. He prayed, for the first time in his life, not even knowing that he had started, and to no one in particular, that someone would save him from his current self... A voice, not of his own, began ringing deep within his mind. Stern, yet soothing it asked, "Do you believe you could be a better mother?"

"Yes," The Keeper replied. "Yes..."