Dreams fall into three categories:
1-Those which come from Allaah. These are a means by which Allaah gives glad tidings to His believing slaves in this world after the cessation of Revelation.
2-Those which come from the Shaytaan, in which the Shaytaan tries to gain power over the sons of Adam and cause distress to those who believe. The Prophet (peace and blessings of Allaah be upon him) has taught us how to protect ourselves from his evil, and he has told us that these dreams do not cause any harm to the believer who observes the etiquette taught by the Prophet (peace and blessings of Allaah be upon him). 25768
3-Dreams that come from the subconscious, in which the sleeper sees his own thoughts and ideas that reflect what is happening in his day-to-day life, as mentioned in this question.
It seems that this sister is in love with this man and wants to marry him, but her parents are refusing this marriage. So in her dream she sees herself with her beloved as she would like to see him in real life.
Finally, I advise the sister to fear Allaah and to obey her parents in what is right and proper. She should strive to choose a husband who is suited to her from among those who are righteous and trustworthy.
Similarly, she should ask Allaah to bless her with a righteous husband who will make her happy, and may Allaah bless them with righteous children who will be a help to them in this world and will store up reward for them in the Hereafter.
And Allaah knows best.