Praise be to Allah.
The relationship of an engaged man with his fiancée is the same as a man’s relationship with any woman to whom he is not related: he is not allowed to enjoy any kind of physical relationship with her whatsoever, until the marriage contract with her has been completed.
If it is asked what kind of relationship the husband can have with his wife after the contract has been completed and before the wedding party, the answer is that he may enjoy a full husband-wife relationship, including looking at her, kissing her, being alone with her, travelling with her, having intercourse with her, etc.(al-Lajnah al-Daa’imah li’l-iftaa: Fataawa Islamiyyah, 3/154).
For more information on the Sunnah (way of the Prophet (peace and blessings of Allaah be upon him) in weddings, and what is done during the celebrations, you can refer to the questions under the heading of Nikaah (marriage) in the Fiqh (Jurisprudence and Islamic rulings) section of this Website. If you have any further questions, please feel free to contact us again. And Allah is the source of strength.