If the questioner asks "before marriage" is before the wedding reception, but after the marriage ceremony (ijab), then this is not sinful. Because, with the marriage ceremony, then a woman has legitimately become a wife, although not held wedding receptions. As for if the relationship is done before the marriage ceremony, ie during the past or earlier, then it is forbidden. A man should not have fun with a non mahram, either by talking, looking or alone. Prophet sallallaahu 'alaihi wasallam said, "Never a man alone with a woman unless the woman is with her mahram and not a woman traveling far, except with her mahram
