Dr. Rajab Abu Mleeh stated that sincere repentance is required of any Muslim who committed such a grave sin. Sincere repentance requires giving up the sin one has committee, showing deep regret about it to Allah and to resolve not to do it anymore. All these elements of penitence must be rightfully observed in order that Allah accepts such repentance.
With regard to marrying the girl after she had embraced Islam, it is permissible after a sincere repentance to Allah by both the man and the lady, but one should be sure that she becomes a practicing Muslim and she is suitable for a Muslim man as a wife.
A Muslim should not downplay good manners and straightforwardness when he intends to get married.