This story is a sequel to A Lascivious Rainbow Dash and a Shared Bath in Tomato Broth
Rarity wakes one night to find that her mane has detached itself from her head and packed its bags. Her mane tells her that it is leaving to pursue new ambitions, alone, without her. Their time together is at an end, it tells her, but the blissfully sweet years they shared will never be forgotten. Before it says its final farewell, they make love together one last time under a moonlit starry sky.
This was written as a standalone story. Reading the previous story is entirely unnecessary.