Matthew Poole and continuators on Esther 2:16

16 So Esther was taken unto king Ahasuerus, into his house royal , in the tenth month (which is the month Tebeth) in the seventh year of his reign.

And into his bed, as is implied. To which it is not strange, if she, though a vertuous person, did in those circumstances yield, considering the infirmity of humane nature, and of that sex, and the state of those times, when plurality of Wives were permitted, and Concubines were owned as Wives; and these Virgins were by this action made his Wives or Concubines. Besides it is not known to us whether Mordecai and Esther had not direction or a dispensation from God in this matter; it being certain that God can dispense with his own positive laws.