What is the ruling on having thoughts of intercourse even before marriage

Thinking about this matter before marriage is of no
benefit. Rather it is harmful, because it usually leads to the provocation of sexual
desire and doing something that is not right in order to fulfil this desire. Try to get
rid of these thoughts and keep yourself busy with the remembrance of Allaah (dhikr),
issues of knowledge and working to propagate the cause of Islam.

We ask Allaah to help us and you to do all that is good.