Our Rabbis teach us that when the couple stands under the chuppah, all their sins are forgotten. The custom to fast on the day preceding the wedding, and to recite the vidui (confession) prayer indicate the parallel between a wedding and Yom Kippur. In the mixing of the two cups of wine, that of Birkat Hamazon and that of the blessings for the couple, we see another parallel, this time to the sacrificial service of Yom Kippur.