What is the ruling on dealing with one's fiancé as if he were a husband?

Treating a fiancé as a husband without a marriage contract is zina (fornication/adultery). Engagement is merely a promise of marriage and does not make anything permissible for the suitor except looking at his fiancée. The fiancée remains under the ruling of a stranger (non-mahram (definition)); therefore, it is not permissible to be in seclusion with her or to touch her. Conversation with her should only be when necessary, within the bounds of modesty and seriousness. Treating a fiancé as a husband is a grave error and a major sin. Whoever has done so must repent and strive to learn the matters of her religion.