What is the significance of Beloved constantly needing sugar after she has come back to Sethe? She flies into a rage and destroys things without it.

Beloved is the representation of guilt and sadness Sethe
carries with her permanently about what she has done to her children to keep them from
slavery.  Beloved's constant need for sugar is the representation of Sethe trying to
make up for what she's done, to placate and spoil the Beloved she has denied life to, as
it were.  She spends money foolishly, money she doesn't have, and acts out of guilt and
shame at Beloved's every whim and need because it is the only way her character can live
with herself and the crime she's committed.

While, as
readers, we sympathize with and feel the cruel victimization Sethe has gone through in
her life, knowing the ugly truth at the end of the story makes it difficult to forgive
her - as difficult as it is for Sethe to forgive
herself.

Beloved is her permanent, immature and enraged
reminder.