I have seen some Orthodox weddings in which the groom steps on the bride's foot. What is the source for this strange custom?
He relates as follows (trans. by Israel Abrahams, Jewish Life in the Middle Ages, pg. 203 fn. 4):
If the bridegroom places his right foot over the left foot of the bride when the seven blessings are being said, he will rule over her all her days, she will be obedient to him, and will hearken to all his words. If the bride is careful to set her left foot over the bridegroom's right, she will rule over him all her days. Now it happened that the bridegroom put his right foot over the left foot of the bride during the seven blessings, to gain dominion over her, and when the bride told her father what had occurred, he advised her that when the marriage was about to be consummated, she should ask her husband for a glass of water. This gave her the dominion all her days, and the expedient is an excellent antidote for overcoming the influence of the placing of the foot by the bridegroom, and the bride can thereby obtain mastery.
Midrash Talpiyot of Rabbi Eliyahu HaCohen of İzmir (d.1729) also quotes the Chesed Le'Avraham here. The Nitei Gavriel here adds that authorities such as Rabbi Shaul Rosenberg objected to the custom as a lack of faith in God, and also some point out that if the bride would be a Niddah at the time of the chuppah this would be halachically problematic.
Solomon Maimon describes this custom at his own wedding in the mid-1700s, noting that he read of it in a Hebrew book. Given that (as described below) his wife was also aware of this, it seems unlikely that it was an obscure custom that he had just chanced upon in his reading.
The Autobiography of Solomon Maimon p. 41
I had once read in a Hebrew book about how one half of a married couple could gain power over the other half for life. The book said the husband should step on his wife's foot at the wedding; if both parties attempt to employ this strategy, the first to do the stepping will get the power. When my bride and I had to stand next to each other during the wedding, I immediately remembered the tactic, and said to myself: You must not squander this chance to achieve lifelong power over your wife. I was ready to step on her foot, but something – whether fear, or shame, or love – held me back. While I was being indecisive, I felt my bride's slipper crush down on my foot with such force that I would have screamed out loud if my sense of pride hadn't stopped me. I saw this as a bad sign, and thought: Providence has decreed that you will be your wife's slave. You will never break free of her chains. Given my cowardice and the boldness of my bride, the reader can see how this prophecy had to come true.