In "Animal Farm," why did Mollie run away?
To answer this question, take a look at chapter 5. At the beginning of this chapter, it is reported that Mollie has been very "troublesome." She is often late for work, for example, and complains of "mysterious pains." It is also noted that she spends lots of time at the drinking pool, gazing at her own reflection.
In addition, Clover has seen her talking to one of Pilkington's men and letting him stroke her nose. When Clover takes a look at her stall, she finds sugar cubes and ribbon hidden amongst the straw.
It is after this conversation with Clover that Mollie disappears. This shows that Mollie runs away because she is more interested in sugar lumps and ribbon than adhering to the principles of Animalism. Mollie is, therefore, materialistic and prefers to be with people who pamper and indulge her, regardless of the political implications. It is very clear that she has no interest in working for the pigs and obeying their rules.
On a deeper level, Mollie symbolizes the political defectors who refused to be part of the Soviet regime, choosing instead to leave the country and start a new life abroad.
Mollie runs away from the farm because she has never supported the rebellion. Mollie loved being under Mr. Jones' rule because she got plenty of sugar and she was allowed to wear ribbons in her hair. She got to be a pretty horse, all show- no work. Under the regime of the pigs Mollie was not only denied her sugar and ribbons, but she was now also required to work! She had trouble getting up early for work and she often liked to quit early. Finally in Chapter 5 Mollie is confronted by Clover about her laziness and her whereabouts during work. The confrontation drives Mollie to run away from the farm so that she could go somewhere where she could finally have sugar and ribbons.
Mollie is representative of those who are too vain and materialistic to care whether or not they are free. Mollie represents those people who would rather be led under a dictatorship than work to be liberated.