What is the ruling of the Sharia on a brother's refusal to marry off his sister to a suitor of good character and religious commitment, while the mother agrees, and is it permissible for the sister to marry herself after reaching the age of majority in a European country, despite her fear of her brother's reaction?

The girl's brother does not have the right to prevent her from marrying a suitable man, as the Prophet (peace be upon him) said: "If someone whose religiosity and character you approve comes to you proposing marriage, then marry him. If you do not do so, there will be tribulation on earth and widespread corruption." The age difference is not an impediment. The ideal solution is to convince the brother by involving people of high standing and relatives. If the girl finds someone in her family whose religiosity and character she approves of, there is no harm in accepting him to please her brother. If she does not find such a person, she has the right to marry the one she loves if he is suitable for her, and in this case, the brother becomes an 'adil (one who unjustly withholds consent), and guardianship transfers to the next in line. The girl must know that she cannot marry without a guardian, for the Prophet (peace be upon him) said: "Any woman who marries without the permission of her guardian, her marriage is invalid."