It was an unfortunate truth; some types of ponies simply lived longer than others.
The thought had occurred to Twilight several times once she met her Ponyville friends; Applejack was the first to develop wrinkles around her eyes and muzzle, the first to lose weight and eat less. One day, which came sooner than Twilight thought (hoped) it would, she bucked her last tree.
She never did fully recover from that injury; by this point, her youthful ability to bounce back from whatever hit her had gone decades ago. The thing that made it all better was Rainbow Dash, who was even more restless than her on a good day; years of being a Wonderbolt had made her familiar with many different injuries, and she seemed to know just what to do for the Earth pony to keep her from being bored to tears.
Even more time passed. Cadance had had her second foal, a unicorn filly with a pale blue coat, magenta and purple streaked mane, and bright golden eyes. "Dad's eyes!" Shining had said proudly. "We're thinking of naming her Sunlight Sparkle."
It was supposed to be a joyous occasion, and for the most part Twilight had a wonderful time, but she couldn't ignore how much older her brother was already looking than Cadance, who looked the same as she always had.
The day finally came when Spike, now a leggy, lanky adolescent who looked too small for his wings, breathed a scroll into his claws. Twilight's heart nearly stopped as she laid her eyes on it. "Oh no..." she whispered.
The scroll was tied shut with a single, simple white ribbon. Somepony she knew had died.
Her large purple eyes filled with tears as they ran over and down the length of the scroll. Her magic faltered, making the scroll shake as she rolled it back up. Her eyelids fluttered shut.
"Twilight?" Spike's warm claws against her wing were what made her tears fall.
"Dad's...he's..." She couldn't continue. Spike, now taller than her, gently pulled her into his arms, where she buried her face against his shoulder and broke down into quiet sobs.
She was the one who organized the funeral. Shining Armor, bless him, wasn't much use; her poor brother was a sobbing, sniffling mess through the whole ordeal.
Cadance more than pulled her weight. She was the one who offered emotional support to Night Light's friends and family. She was the one lead the funeral ceremony and oversaw the will reading.
Princess Celestia helped Twilight decide where the funeral would be held; a big, beautiful temple just outside of Canterlot's borders, which oversaw a peaceful old cemetery. Her family hadn't been wealthy enough to afford a family mausoleum or plot of land; Celestia was the one who assured her that her father's remains would be buried near his own parents. She helped Twilight Velvet, quietly, gently bringing up the topic of her own death; she was the one who gently coaxed out the fact that, when she finally went, she would like to be buried next to her husband.
Twilight had unending gratitude for the both of them. But it was her Luna, her wife of ten years by that point, who was truly there for her.
She was the one who would drape a wing over Twilight's back, reassuring her in whatever decision she made for the funeral, what time it would be, who would speak when, what food and drinks to serve at the wake afterwards. She was the one who stood next to Twilight, hoof gently brushing hers, as Candance spoke, strong and clear, before the audience of crying ponies. Because Twilight knew she was there, she was able to speak about her late father without sobbing. When Twilight's jaw dropped as she learned that Night Light had left her his entire collection of books, Luna nuzzled her behind one of her ears, a tiny, quiet gesture that spoke loudly.
At the end of the day, once the two retired to Luna's quarters in the castle, it was Luna's arms that Twilight fell into, finally letting herself cry in full. Not the quiet, shocked sobs Spike had seen; not the mild tearing up ponies had seen up to and during the funeral. Luna was the one who saw the Princess of Friendship dissolve into a teary, snotty mess against the black satin of her mourning dress.
"I'm so sorry, My Love," Luna murmured, rubbing her back with a hoof she'd just freed from one of her silver horseshoes.
"Does..." Twilight's words caught in her throat, interrupted by an onslaught of hiccups. "Does it...ever stop hurting?"
Luna sighed, rustling some of the blue and purple hairs of her wife's mane. "No," she said simply. "My own mother and father have been gone for...a long time now. The pain never really does go away, but I promise...it will become easier to live with."
As Twilight hid her face beneath Luna's glittering mane, she continued. "But for now, allow yourself to feel that pain. Cry as often as you need to, for as long as you need to. Know that you are not alone; we are all here for you now." She pressed a gentle kiss to Twilight's neck. "I am here for you now."
And even through all the hurt and sorrow, that was what Princess Twilight Sparkle wound up needing to hear. It was exactly what she needed.