It is an ancient custom that a groom be called up to the Torah on the Shabbat before the wedding, or in most Sefaradi communities the Shabbat after. In Yiddish this is called “Aufruf” which literally means “calling up” to the Torah. The origin of this custom is given in the Midrash Pirkei d’Rebbe Eliezer (ch.17):
“[King] Shlomo how great is the quality of loving kindness before the Holy One blessed be He, and when he built the Temple he built two gates, one for bridegrooms and one for mourners and the excommunicated. And on Shabbat the people of Israel would go and sit between these two gates. If someone went in the gate of the bridegrooms they would know that he is a bride- groom, and they would say, “May the One Who dwells in this house gladden you with sons and daughters… From the day the Temple was destroyed, the Sages instituted that bridegrooms and mourners go to Beit Knesset and to the Beit Midrash, and the people of that place see the bridegroom and rejoice with him, and they see the mourner and sit with him on the ground, in order that all Israel should fulfill their obligation to do acts of kindness”
This passage is cited by the Tur in Yoreh Deah 393.
The custom of calling the chatan up to the Torah sends a powerful message of belonging and context. First of all, there is the belonging to the community and to the Jewish people as a whole. The synagogue is the House of Gathering for the entire congregation, while the above midrash reminds us that it is a reminder of the Temple which was the focus for entire nation. This theme of communal belonging is reinforced by the mitzva of “sheva berakhot” with its requirement for a quorum of ten and for a new face each time.
There is also emphasis on the connection to the chain of generations. We may note the special blessing to the chatan that he may merit sons and daughters.
Finally there is the connection to the Torah. The chatan is not only present in synagogue, he is also called up to the Torah. Indeed, a midrash suggests a connection between the idea that “a bridegroom is like a king” and the commandment that a king needs to have a Torah scroll accompany him at all times. (Midrash Talpiot, cited by Rav Gelbard and others.)
Many have noted the stark contrast between the message of belonging sent by the custom of sheva berakhot with the message of independence sent by the common secular custom of a honeymoon; we may add to this the contrast between the sanctified public rejoicing of the Shabbat Chatan with the private, sometimes even furtive, nature of a secular bachelor gathering on the eve of the wedding.