Can envy be a reason behind recurrent miscarriages, failure to conceive, lack of fertilization of ova by sperm despite their soundness, and the physical pains suffered by the questioner, especially given that there was someone who wished to marry her husband and took a stand against her?

Envy (Hasad) and the evil eye (Ayn) can be causes of infertility. The cure lies in reciting the Quran, performing Ruqyah Shar'iyyah (Islamic exorcism/healing), prayer (Salah), and supplication (Du'a) with full presence of heart and certainty of response. Consistency in acts of obedience and not despairing are important, while also considering that the cause might be organic or a matter of time. Reciting Surat Maryam to strengthen hope in Allah's ability to bestow righteous offspring is permissible, provided it is not done with the intention that it is part of the prophetic guidance for supplication.