In many Jewish communities it is customary for the groom to fast the day before the wedding. This is because according to the Talmud Yerushalmi (Bikkurim 3:3), on the day that a person is married, all of his or her sins are forgiven. The fast is a sign of repentance and atonement. "With marriage one is beginning a new phase in life. Marriage involves a complete change in lifestyle, and the person is given a chance to start it with a pure soul. The love that the couple has for one another on their wedding day can annul any misplaced passion that they had in the past". The couple also fast for the future, to deserve "divine guidance that they may be able to overcome problems as they arise" (Rabbi Aryeh Kaplan, Made in Heaven, page 83). In Ashkenazi communities this fast is very important.
In most Sephardic communities, however, the custom is not to fast. Rabbi Obadya Yosef is very clear about this point and recommends the Sephardic grooms to avoid fasting. Other Sephardic rabbis like Rabbi Chayim haLevy are even stricter and they forbid the groom to fast. The reason is that they consider that the couple has to be strong to endure all the pressure of the wedding, the party, etc. The process of Teshuba, they reason, can still be achieved by devoting themselves in this important day of their life to study Tora and elevate prayers to God. Rabbi Yosef also recommends that if the groom and bride still desire to fast, they should consider to do a "a fast of words" (ta'anit dibbur) not of food, which represents an even higher sign of self control, repentance and contrition.
In many communities, Ashkenazi and Sephardic, it is customary that the bride and the groom recite the Viduy (prayer of regret and confession, see here) from the Mincha service of Yom Kippur or other similar texts.
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