Retrieving holy sparks from impurity

בענין שנשאת אסתר לאחשורוש.

Regarding the matter of Esther being married to Achashverosh.

The Sefas Emes addresses the difficult question of how Esther, a righteous woman, came to be taken into the house of a wicked king.

נראה שהי' צריך תיקון זה לתקן החטא שנכשלו אז בנשים נכריות כמ"ש בעזרא.

It appears that this tikkun (rectification) was needed in order to repair the sin in which they had stumbled at that time - taking foreign wives, as is written in Ezra.

In the generation of the return to Eretz Yisrael, Bnei Yisrael had failed by marrying non-Jewish women. Esther's seemingly tragic marriage was in truth a hidden avodah to set right that very breach.

והוצרכה אסתר להוציא ניצוצי קדושה שנתפזרו בסט"א ע"י חטא הנ"ל:

And Esther was needed to extract the nitzotzos kedushah (holy sparks) that had been scattered into the sitra achra (the side of impurity) through the aforementioned sin.

By entering the very domain of the wicked king, Esther was able to gather up the holy sparks that the earlier intermarriage had cast into the realm of impurity, redeeming them and restoring them to kedushah.

Summary: Esther's marriage to Achashverosh was not a stain but a hidden tikkun - descending into the place of impurity to retrieve the holy sparks scattered there through the sin of foreign wives, mending the breach of the earlier generation.