It was a mostly normal day in Ponyville. The sun was shining, the birds were chirping, and somepony was being overly dramatic in Carousel Boutique. What was unusual, however, was that the pony in question was not Rarity. Rarity was sipping tea.
Twilight Sparkle, on the other hoof, was frazzled. “I just don’t understand it, Rarity! I don’t know of any ailment that works this way. I’ve read a dozen books both mundane and magical and nothing explains the symptoms! Applejack was fine a month ago, but every day I see her it’s getting worse. And now? Now I think I have it, too!”

“Let me see if I understand you correctly,” Rarity said softly. “When Applejack is alone, she is fine. When she is with other ponies, she is fine. When she is around you, you notice that she becomes nervous.”

“I didn’t say nervous, did I? I have the list right here. She first showed signs of minor aphasia. I thought little of it at the time. Maybe she was just tired. But it didn’t go away.”

“You told me this already, darling. And you can think of no other reason for this besides fatigue?” Rarity took another sip of her tea to conceal her faint smile.

“I can think of plenty of reasons! Except she doesn’t have seizures. She hasn’t done anything that could cause a concussion. She doesn’t recall any odd magical explosions or strange plants or anything like that! And that’s only the first symptom. After that, I started paying closer attention. Her ears flicker all over the place. Her gait becomes less controlled. Finally I couldn’t take it anymore and told her I needed to examine her! Her heart was racing, she wasn’t breathing deeply enough, and her tail wouldn’t stay still. And then?” Twilight inhaled deeply, “Then, I realized that I was suddenly experiencing the same thing. And every time I see her, it comes rushing back! What if I’m infected? What if I just spread it to you? Everypony in Equestria could be at risk unless I can figure this out!”

Now, some ponies in Equestria might show sympathy for their friend’s clear distress. Rarity was not one of those ponies. Rarity? She giggled. Twilight glared at her.

“How can you make light of this? This is serious!”

Rarity reached across the table to take Twilight’s hoof. “You are right, Twilight. It is serious. But not in the way you think." Rarity rose from the table, and nodded briskly. "Well, I know what the cure is. Come with me.”

Twilight’s worry transformed instantly to curiosity. “You know? Then tell me!”

Rarity hmmphed and shook her head. “You will see. Follow, and no talking.” The two went into Ponyville proper, making their way through the streets and towards the center of town.

“The marketplace?” Twilight broke the silence as Rarity led her through the small crowd of ponies shopping for food and more. “What’s in the marketplace?”

“Ah, ah, ah! What did I say? No talking!” They crossed the market towards a familiar stall, and Rarity stopped before it. “Big Macintosh, can you do without Applejack for a moment? We must speak with her.”

“Eeeyup.”

“Very good. Come here please, Applejack.”

“Now hold yer horses, Rarity. What’s this about?”

“Just come. You will understand.” Rarity waited impatiently for Applejack to exit, and then led the trio beneath a tree. “Twilight. Are you experiencing the symptoms now?”

Twilight silently nodded her head. Applejack took one look at Twilight, and scuffed a hoof in the dirt.

“It is true, then!” Rarity’s voice shook with ardor, “You two HAVE been afflicted by a most dreadful malady! There is but one cure. Twilight, you must kiss Applejack, or it will only grow worse!”

“Kiss her?! But -”

“No buts, Twilight! Do it!” Applejack said nothing, just stood there with her mouth open, lips moving, but no words coming out. Twilight took one last look at Rarity, and then sighed and leaned in. Their lips met, tentatively. They drew back moments later, blushing.

The second time, there was no hesitation.

It was a mostly normal day in Ponyville. The sun shone, the birds chirped, and two little ponies happily planned their very first date.