All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
Paradise is among the matters of the Unseen and we can only speak about it with evidence from the Book of Allah and the Sunnah of the Prophet .
Regarding the subject you have asked us about, as far as we know, there is no single person in Paradise.
Abu Hurayrah narrated that the Prophet said: “There is no single person in Paradise.” [Muslim]
Therefore, if an unmarried woman enters Paradise, she will get married, but we have not come across any evidence about the method of how she will get married and whether or not she will be given a choice to choose whomever she wishes.
Nonetheless, a woman should be concerned about how to enter Paradise and strive to do the deeds that will make her achieve this precious wish, and afterwards, she will find eternal bliss and happiness.
Allah knows best.