A few minutes into their day together at the spa, Celestia begins to talk with Luna about the nightmares. This is exactly what she feared. "Luna, you need to learn to share important things like this with me. I'm your sister. That makes it even more important that you talk with me. I'm not going to abandon you, you're not going to turn into Nightmare Moon. I promise. Promise." Celestia's voice begins to shake. "Why would I ever abandon you? You being banished for so long shook me to the core and I don't want to feel pain like that ever again." Celestia begins to cry. "You know that."
"Shh, shh," responds Luna as she goes over and embraces Tia in a hug. "I know you would never abandon me. My fears, however, they are a monster all their own, even worse than the Tantabus sometimes."
"You see," says Celestia with a smile through the tears, "was admitting that to me so hard?"
"Yeah, it wasn't, you're right," responds Luna as a small smile peeps across her face. The two share another hug.
A few hours later, the two finish up at the spa and go on a nice fly together through the sunset sky. "It's so pretty," sighs Luna. "Sunsets like these always erase all my fears and drown out all my sorrows."
"I'm glad to hear that," responds Celestia. A few hours later, the two land back on the castle balcony and Celestia retires for the night while Luna goes into the dream realm for several hours and looks over ponies dreams. Watching as they dream and helping with their nightmares if they have any.
"Now if only I could do this for my own dreams and my own nightmares," sighs Luna. "That would make things so much easier."
A few hours later, the sun rises and Luna exits the dream realm and goes and turns in herself. As she sleeps, she doesn't have any nightmares because her dream projection of herself is actively beating those nightmares into oblivion. As her dream projection does that, Luna continues to sleep peacefully. She's relieved. Somehow, her mind finally adjusted and realized that the nightmares were harming her and are now working against them, hopefully for good. She can't wait to tell Celestia about all this, but first, it's time for a good night's sleep.