NOTE: This is my head canon for the MLP universe.

Immortality would be the worst curse imaginable. At first, it's a power thing. If you're immortal, you can accomplish so many things, see all of history, and experience the end of time. But with whom? Your family? Dead. Your friends? Also dead.

That's why the alicorns of "My Little Pony" must have cruel existences. Sure, Celestia has Luna but who does Twilight have? In the series finale, we see her friends aging and her coming into her alicorn power. She hasn't aged, though. She had no wrinkles and no gray hairs.

It also makes you wonder about Cadence. She'll have her daughter for the rest of her life but not her husband. Shining Armor isn't immortal. Whenever a pony is turned into an alicorn, it's not an honor; it's a curse.

Twilight's feeling that curse here. Though she's surrounded by her loved ones, she cannot see them. I will forever pity her and the life she was forced into. Then again, would anyone want to be ruler of Equestria if it meant they'd watch everyone they know shrivel to dust?

Dark and depressing, I know, but that's what feeling angsty will do to a person.