Is it permissible to marry a person who is suitable and desired by the girl, while her father rejects him for flimsy reasons and does not listen to anyone's advice?

It is impermissible for the woman's guardian to prevent her from marrying a man who is suitable in terms of religious commitment and character. If he does so, he is deemed to be a 'adil (one who unjustly prevents marriage), and his guardianship is forfeited. It is advisable to involve influential people to persuade the guardian; otherwise, the woman may refer the matter to the judiciary.