What happens to Mollie in Animal Farm?

Mollie runs away to enjoy the comforts of living with people. 

Mollie is really more of an ornamental animal.  She does not have many uses, and she enjoys being a pet to the people.  When the worker animals drive out the humans, Mollie worries that she will not live a pampered lifestyle any more. 

Mollie is selfish and self-centered.  From the minute she is introduced, this is clear. 

At the last moment Mollie, the foolish, pretty white mare who drew Mr. Jones's trap, came mincing daintily in, chewing at a lump of sugar. She took a place near the front and began flirting her white mane, hoping to draw attention to the red ribbons it was plaited with. (Ch. 1) 

Old Major tells the other animals that they are better off without humans.  Humans take and do not give.  They consume without producing.  He says that the humans are taking advantage of the animals, stealing from them and abusing them.  He wants them to be self-sufficient. 

Mollie asks Snowball if there will still be sugar after the rebellion.  The animals consider that a stupid question.  Snowball tells her that sugar is not a necessity, so of course they will not have any.  They have no way to make sugar on the farm, and they do not want to trade with humans.  Snowball tells her that her ribbons are “the badge of slavery” and she will not wear them (Ch. 2).  When they tour the house, Mollie steals a ribbon. 

Mollie is useless on the farm.  She does not like work.  She doesn’t wake up early enough, and she knocks off work early by pretending she stepped on a stone.  She makes “excellent excuses” so she generally gets away with it (Ch. 3).  When the animals learn to read, Mollie refuses to learn any letters but the ones that make up her own name.  During the battle, she hides under hay at the sound of the first shot. 

Mollie is spotted talking to Mr. Pilkington, a neighbor, through the hedge.  She lets him stroke her nose.  Clover is troubled by this, but Mollie denies it.  Later, they find her hiding ribbons.  

Three days later Mollie disappeared. For some weeks nothing was known of her whereabouts, then the pigeons reported that they had seen her on the other side of Willingdon. She was between the shafts of a smart dogcart painted red and black, which was standing outside a public−house. (Ch. 5) 

In the end, Mollie couldn’t cut it on the farm.  She wanted to be pampered by humans.  She did not want to work her fair share.  Mollie cared more about ribbons and sugar cubes than the tenets of Animalism.  She is a defector, glad to go back to the enemy.