It's wrong to take joy in the suffering of others.
Jen has a huge rivalry with Alice and sees that Alice has fallen in a mud puddle.
Jen wants to respond to Alice's fall.
Jen reaches out to help Alice up and asks if she is alright.
Jen points and laughs and claps at seeing Alice fall in the mud.
Everyone sees Jen as the better person, and she makes more friends.
Jen's friends find her needlessly cruel and petty and stop hanging out with her.