How can a woman persistently supplicate for her marriage to a married man toward whom she has feelings?

"Insistence" means to approach something with perseverance and continuous commitment. It means to increase and repeat supplication, insisting upon Allah by repeatedly acknowledging His Lordship and Divinity, and His Names and Attributes. Insistence is achieved by saying "O Lord, O Lord" and repeating the beautiful Names of Allah, and it is one of the greatest reasons for the acceptance of supplication. You both have done well to be cautious about falling into what is forbidden, so continue with that until Allah facilitates the completion of the marriage, for it extinguishes the fire of love. If the marriage does not take place, then let each of you go your separate way, and ask Allah to grant you someone better than him.