A few quotes from the Rabbi on 'Traditions of the Fathers'
in which he teaches the reason for which the Sabbath preceding the Giving of the Torah is called the Bridal Sabbath
This Sabbath is called the Bridal Sabbath, indicating the giving of our Torah, on this date and in those days, on the Festival of Shavuot. Truth is, one should know why it was so named, and not [named] the Sabbath of the Giving of the Torah…In my modest opinion, the reason is as follows: It is common knowledge that towards their wedding, a bridegroom spends large amounts of money on his bride because of his love for her, sends her clothing and jewelry, and may also buy her a bonnet for her head, and pretty shoes of good quality…which is not the case after the wedding… He does love her, although it is not the same as the moment of the marriage…It is thus clear why this Sabbath is called the Bridal Sabbath. It signals the Giving of the Torah from Sinai in our day, at which moment the reception of which will be with great love…and not as it might be later, after the marriage as it were.
Ish Mevin, Volume I, pp.45a – 46a, Haim Abraham De Sigora Press, Izmir, 1889