There are so many Disney princesses, and they all have their own stories. They also all live happily ever after.
Cinderella was a plain girl who was treated badly by her stepmother and stepsisters. When her fairy godmother granted her wish to go to the ball, she fell in love with the prince. Luckily, he felt the same way and, after a tiny setback, they lived happily ever after.
Snow White was a princess who lived with her evil stepmother (the queen), who was jealous of Snow White's beauty. Snow White ran away into a forest and lived with 7 dwarfs. The evil queen came and tried to poison Snow White. She was saved by her prince who gave her true love's kiss, and they lived happily ever after.
Ariel was a mermaid princess, and she was very curious but forbidden to leave the sea. When she rescues and falls in love with a human prince, she wants to become human to be with him. The evil octopus Ursula tricks Ariel to ruin her chances with the prince. Long story short, Ariel wins, and the prince and she live happily ever after.
Sleeping beauty was a princess who was cursed by an evil fairy. Because of this, she goes into hiding with 3 good fairies. When the curse comes true, she goes into a deep sleep, but is rescued with a true love's kiss from her prince. They live happily ever after.