It may seem a little funny for hundreds of people to gather in celebration of one couple's marriage. After all, the decision to marry is arrived at through a very private, internal process that can only be appreciated by the man and woman themselves. And the experience of married life is also extremely personal. Why does Jewish tradition celebrate marriage communally? Does it emphasize communal life at the expense of privacy, and the delicacy of personal experience?
The Torah actually stands out, as a drama, for the importance and power it gives to private experience. Whereas in Greek drama the climax takes place in the presence of a chorus, Torah's heroic moments take place hidden from the public eye, when Avraham Avinu tells his servants to stay behind as he climbs up Mount Horiah to sacrifice his son Yitzchak, or when the Cohen Gadol enters the Holy of Holies alone on Yom Kippur. These moments when we're alone with Hashem can be the most defining.
But while the quality of the experience of marriage may be defined by what goes on in private, it cannot be initiated without witnesses. In fact, marriage, specifically, requires witnesses for the event to carry any halachic significance, as opposed to other kinds of agreements where witnesses only serve to prevent lying. No matter how committed they are, and how extensive and poetic their vows, a couple is not married unless there were two kosher witnesses involved.
The concept of private connection in Judaism is encompassed by the term קדושה "Kedushah". Weakly translated as holiness, it means a special, private and all-absorbing kind of connection. Kedushah always includes two aspects, like two sides of a coin. The first is a complete and total separation and removal from everything, and the second is a unique and specific connection formed by virtue of that separation. It's a theme that appears throughout all of Judaism, most apparently in the relationships of man and woman, and Israel and G-d. For example, Marriage is made up of two parts, the first is called "Kiddushin," which is a commitment of fidelity, today customarily an exchange of a ring, and the second is called "Nissuin," which is the first official private co-inhabitance of the married couple.
A Jewish home is compared to the "Mishkan," the holy temple. The Mishkan was a microcosm. Every part and every vessel paralleled different parts of the world, from the stars to the earth. The Mishkan is the place where Hashem's presence is most palpable. The Jewish way to establish a relationship is to make it more than an important part of our life - it has to be a whole world unto itself.
Kedushah is the true way to be totally connected and present in the world of the relationship created solely for that purpose. It is because marriage is founded on Kedushah that there is nothing shameful about it and it's not an excuse to close the doors so no one will intrude. Even though it is essentially a private world, Kedushah is also the secret of all Jewish life and continuity. The Jewish people as a whole live and thrive on Kedushah, and each individual soul thrives on its connection to the eternal collective.