The Mishna describes a remarkable Yom Kippur custom during Temple times:
There were no happier days for the Jews than the fifteenth of Av and Yom Kippur. On those days, the young women of Jerusalem would go out in borrowed white clothes in order to avoid embarrassing those who did not own any…. They would dance in the vineyards, saying: “Young man! Please look and choose someone. Do not look at beauty, look at the family. ‘Grace is deceptive, beauty is illusory; it is for her fear of the Lord that a woman is to be praised. Extol her for the fruit of her hand, and let her works praise her in the gates’ (Mishlei 31:30-31).” (Ta’anit 26b)
At first glance, this seems strange. How can it be that on this awe-inspiring, holy fast day, people were matchmaking? On further reflection, it is not so strange. The marital bond is sacred. Our Sages say that the Shekhina dwells with a husband and wife who are faithful to each other (Sota 17a). Through their loyalty and love, they express God’s unity. This is why God allows His name to be erased in order to reconcile husband and wife (Nedarim 66b). Similarly, Arizal states that the mitzva to “love your fellow as yourself” (Vayikra 19:18), which R. Akiva calls “a great principle of the Torah” (Sifra ad loc.), reaches its ultimate fulfillment within marriage.
Furthermore, the union of a married couple corresponds to the supernal union of God and the Jewish people, as we read, “As a bridegroom rejoices over his bride, so will your God rejoice over you” (Yeshayahu 62:5). R. Akiva said, “No other day was as precious as the day the Jews were given Shir Ha-shirim. For all of the Writings are holy, but Shir Ha-shirim is the holy of holies” (Tanḥuma Tetzaveh §5). Similarly, the keruvim (cherubim) on the top of the ark in the Kodesh Ha-kodashim were in the form of a male and female being intimate. This was to teach that holiness does not constrict life but intensifies it. When the Jews stopped doing what God wanted, the keruvim turned their backs on each other and faced outward (Bava Batra 99a).
These ideas lie at the root of the custom of young Jewish men and women seeking their match on Yom Kippur. They drew upon the unity of God and the Jewish people to find their own union and love, to create holy Jewish homes. Accordingly, married couples must repent on Yom Kippur for any failure to love and pleasure each other properly. True, on the physical level, a couple must separate on Yom Kippur, as they do when the wife is a nidda (9:7 below). Nevertheless, on the spiritual level, their connection is stronger than usual, due to the holiness of the day. This concept is reflected in the laws pertaining to the Kohen Gadol serving in the Temple on Yom Kippur. On the one hand, he was required to separate from his wife for a week before Yom Kippur. On the other hand, an unmarried kohen was not allowed to serve on Yom Kippur at all (10:4 below).
The young women would wait to dance in the vineyards until after the scapegoat was cast away. Since the sins of Israel were forgiven then, it was an especially joyous time. This custom was appropriate at a time when the Shekhina dwelled with the people, and the Temple linked heaven and earth. But since the destruction of the Temple, heaven and earth are not as close together. If people today engaged in matchmaking on Yom Kippur, they would miss out on the primary expression of the day’s holiness.
Nevertheless, it is still proper on Yom Kippur for all singles to pray for a good match, as the very holiness of the day can help in their quest. Often, negative character traits such as arrogance and lust prevent people from finding their true match. On Yom Kippur, when the pure soul is revealed, a person can see his life goals more clearly. He can better determine what type of person would suit him best, and with whom he would be able to build a home of Torah and mitzvot, so that together they will add life and joy to the world.
Perhaps we can reconcile the positions by saying that while the young women did not dance in the vineyards on Yom Kippur, people did engage in matchmaking then. Alternatively, Birkei Yosef suggests that the women danced in the fields at night right after Yom Kippur. R. Shlomo Goren presents a different approach: In the days of the First Temple, the presence of the Shekhina was palpable, and the red thread tied to the horns of the scapegoat, which indicated whether klal Yisrael achieved atonement, would always turn white (Yoma 39a). The Sages had not yet formulated the prayers, so the Kohen Gadol’s avoda and vidui atoned for everyone. Thus, the mood on Yom Kippur was one of joy, and the young women would dance in the vineyards then. In contrast, in the time of the Second Temple, the Shekhina was not perceptible, the red thread did not always turn white, and the Sages had formulated the prayer service. Thus, the mood on Yom Kippur was one of awe, emphasizing judgment, and matchmaking was not undertaken then (Mo’adei Yisrael, pp. 65-66). R. Ḥayim David Halevy says something similar, but the distinction he draws is between Temple times and post-Temple times.
The same mishna states that the phrase “His wedding day” (Shir Ha-shirim 3:11) refers to the giving of the Torah. Rashi explains that “this refers to Yom Kippur, when the second Tablets were given.” R. Tzadok Ha-Kohen of Lublin elaborates: “On Shavu’ot, the [first] Tablets were given through divine initiative, and they were shattered; on Yom Kippur, the second Tablets were given through human initiative, and those tablets endured” (Pri Tzadik, Tu Be-Av §2). The central feature of this “wedding day” of Yom Kippur is that the second Tablets left space for the Sages of the Oral Torah to come up with novel interpretations and enact regulations.