Is it obligatory for a fiancée to separate from her fiancé who insists on anally penetrating her after marriage, despite her knowledge of its prohibition and her desire not to disobey Allah?

The guardian of a girl must not marry her off to a person of bad character or weak religious commitment, because the Messenger of Allah, peace and blessings be upon him, said: "If someone whose religious commitment and character you approve comes to you seeking marriage, then marry him. If you do not do so, there will be tribulation on earth and widespread corruption." It is not permissible for the wife to allow her husband to engage in forbidden intercourse.