Symbolism, Imagery, Allegory
We're sorry to say it, but the circle dance is the closest thing you're going to get to fun in this novel. Kundera describes his participation in it this way:
I too once danced in a ring. It was in 1948. In my country, the Communists had taken power, the Socialist and democratic Christian ministers had taken refuge abroad, and I took other Communist students by the hands or shoulders and we took two steps in place, one step forward... (III.6.1)
The circle dance is a symbol for Kundera of ultimate unity, a brotherhood of people marching together in solidarity and harmony. It's just too bad that at this time, most of these ring dances were held to celebrate something horrible the Communists did to private citizens—or, more precisely, to make people forget about all that nastiness.
Though Kundera has major problems with the Communist Party, he really regrets being thrown out of the "dance." He feels like Satan cast out of heaven, left to fall for a long time before he reaches his awful destination: "Because ever since they expelled me from the ring dance, I have not stopped falling, I am still falling, and all they have done now is push me once again to make me fall still farther, still deeper..." (III.9.5).
Madame Raphael, Gabrielle and Michelle's teacher, also has a great yearning to belong. For her, too, the circle dance means never having to be alone. It means having an immediate society of like-minded people around her at all times: "Madame Raphael, the teacher, clipped that photo from the magazine and gazed at it dreamily. She too wished to dance in a ring. All her life she had looked for a circle of men and women with whom she could hold hands in a ring dance..." (III.5.5).
She really wants that security and happiness, but it turns out that Madame Raphael has been looking for love in all the wrong ideologies. And because her mind is so preoccupied with finding her place in the dance, she turns a mistake into the fulfillment of her purpose.
And that's symbolic, folks. These circle dances represent a kind of idealism that is too divorced from reality to be good for anybody involved. The only place for these people to go is up—up into the heavens, far away from reality.