The Megillah (2.16) mentions taking Ester into the Palace, loving here [more than other girls] and crowning her as the queen but no mention of the marriage or being Achashverosh's wife:
וַתִּלָּקַח אֶסְתֵּר אֶל־הַמֶּלֶךְ אֲחַשְׁוֵרוֹשׁ אֶל־בֵּית מַלְכוּתוֹ בַּחֹדֶשׁ הָעֲשִׂירִי הוּא־חֹדֶשׁ טֵבֵת בִּשְׁנַת־שֶׁבַע לְמַלְכוּתוֹ׃ וַיֶּאֱהַב הַמֶּלֶךְ אֶת־אֶסְתֵּר מִכָּל־הַנָּשִׁים וַתִּשָּׂא־חֵן וָחֶסֶד לְפָנָיו מִכָּל־הַבְּתוּלֹת וַיָּשֶׂם כֶּתֶר־מַלְכוּת בְּרֹאשָׁהּ וַיַּמְלִיכֶהָ תַּחַת וַשְׁתִּי׃
Esther was taken to King Ahasuerus, in his royal palace, in the tenth month, which is the month of Tebeth, in the seventh year of his reign.
The king loved Esther more than all the other women, and she won his grace and favor more than all the virgins. So he set a royal diadem on her head and made her queen instead of Vashti.
Do any sources speak about that?