Can a woman marry someone in the afterlife whom she desired in this world but did not marry, and can they have children in Paradise?

For a woman to wish for a specific man to be her husband in Paradise, if he was married in this world and his wives are among the people of Paradise, then it is not permissible to wish for that. However, if he was not married, there is no harm.

We previously mentioned a fatwa by Sheikh Ibn Uthaymeen prohibiting a woman from supplicating that Abu Bakr or Umar be her husbands in Paradise, because they have wives, and he considered this an aggression in supplication.

Shaykh al-Islam Ibn Taymiyyah mentioned that if a man loved a woman in this world but did not marry her, and he gave charity equal to her dowry and asked Allah Almighty for her to be his wife in the Hereafter, then this is hoped for him. Based on this, there is no harm for a woman to wish for a specific husband in the Hereafter, and Allah knows best whether what she wished for will be fulfilled or not.

As for having children in the Hereafter, scholars have differed on this matter, and the most probable opinion is that there will be no births in Paradise.