In Animal Farm, why was Mollie unable to accept Animal Farm?

It is in Chapter 5 that we are told that Mollie is working
less and less and putting less effort in, and then she
disappears:

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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. A fat red-faced man in
cheek breeches and gaiters, who looked like a publican, was stroking her nose and
feeding her with sugar. Her coat was newly clipped and she wore a scarlet ribbon round
her forelock. She appeared to be enjoying herself, the pigeons
said.

So Mollie exits from
the novel as is never mentioned again.

Unlike Boxer, who
always thinks of others, Mollie is a shallow materialist who cares nothing for the
struggles of her fellow animals. her first appearance in the novel suggests her
personality when she enters the meeting at the last moment, chewing sugar and sitting in
the front so that the others will be able to admire the red ribbons she wears in her
mane. Her only concerns about the revolution are ones prompted by her ego: When she asks
Snowball if they will still have sugar and ribbons after the rebellion, she betrays the
thoughts of old Major and reveals her vanity. She is lulled off the farm by the prospect
of more material possessions that she could enjoy in an animal-governed world, marking
her as one to whom politics and struggle mean nothing.