To see if the Chassan gets dizzy from it. If he does, well, you know what happened when Bnei Yisroel circled Yericho 7 times. Otherwise, he’s probably strong enough for whatever hurdles marriage will present.
What I find funny is the origin of the minhag of the mothers walking around. It started about 25 years ago. Kallas who had long trains needed someone to carry it so it wouldn’t get entangled. So her mother would carry it. Soon you saw the chasans’ mother walking too. Now you see both mothers walk even when there is no train
What is even funnier, is that before 100 years ago, some also had the Minhag that the fathers also went around. Perhaps the mothers’ gowns were too long as well. But anyhow, when you saw that the mother held the train that was a second bird, not the reason.
Some attribute it to the Gemara in Yevamos 62b, Whoever is without a wife is without Simcha, Bracha, and Tova. In Maarav they said, he is without Choma (wall) and without Torah.