Are kisses between fiancés considered haraam, and what is the ruling on a fiancé telling his fiancée, "You have become my wife before Allah"?

The suitor is a stranger to his fiancée; it is not permissible for him to look at her or kiss her. Rather, he is like any other person until the marriage contract is concluded. The Lawgiver permitted him to look at the woman he intends to propose to, initially as a gaze of inquiry. This gaze may occur once or more when needed, and once the purpose is achieved, he must refrain from looking.

What some people do, allowing the suitor to sit with the fiancée without religious guidelines or to be in seclusion with her, is a great abomination and a clear sin. And whoever allows the suitor to sit with a woman under his guardianship and come and go as he pleases is a dayyūth (one who lacks jealousy over his womenfolk).

The girl must repent to Allah Almighty for what has passed, and she should not be deceived by the suitor’s display of affection and love, for what is forbidden has no validity.

The suitor’s statement: "You are now my wife before Allah" is invalid. Engagement is not marriage, and a woman does not become his wife except through a valid Islamic contract that includes the woman's guardian and witnesses. Any excessive looking, seclusion, or kissing during engagement is a grave abomination, and it is a type of zina (fornication/adultery), as stated in the hadith: "The son of Adam has his share of zina decreed for him, and he will inevitably attain it. The zina of the eyes is looking, the zina of the ears is listening, the zina of the tongue is speaking, the zina of the hand is striking, the zina of the foot is walking [towards sin]. The heart desires and wishes, and the private parts either confirm or deny that."