How can one act regarding a father's refusal to marry his daughter to the one she loves, and his insistence on marrying her to another whom she does not desire, given the psychological pressure and suffering for both parties?

The questioner is advised, if he is able to marry and desires to do so, and can convince her guardian, then he should proceed. Otherwise, he should leave her and seek someone else, entrusting his affair to Allah and asking Him for a righteous wife. As for the girl, if she is coerced into marrying someone she does not desire, she should try to convince her father. If she is forced, she can refer the matter to the judiciary to annul the marriage. However, if the young man is religious and of good character, she should absolve her father by accepting him as a husband, for this young man might be better for her.