Luna and her long distance consort, (currently nameless), the sphinx from the East Deserts. He is a loyal knight of the king but fell for the princess of the night. He is very young but he is an accomplished solider of the Desert lands where Sphinx's live and thrive. He is Luna's consort though it can't be announced officially since his loyalty is to his king. Luna was a hard catch but his determination wore her down.
They met when Luna had to go to the Desert lands for a trade deal. She had to sneak into the country due to some weird rule about mares being subservient or something and had to disguise herself as a unicorn. She hired (nameless) as her bodyguard/guide at a bar after he rescued her from some thugs. They bonded on the way there, him showing her the correct way to navigate through the desert and her teaching him fighting techniques lost to time. Neither knew the others true identity until they arrived at the Sphinx's palace.
Note: Sphinx's worships the Sun, due to how closely tied they are to the Sun for biological reasons. As such, they revered Princess Celestia as a Goddess. Princess Luna was basically forgotten since her sister was raising the Sun and Moon for centuries.