Chelek Tes vov. Pg 331

In the story of Yehuda and Tamar, Tamar asks for Yehuda’s signet ring, cloak, and staff, items that marked his unique identity. The Rebbe explains that the ring with its seal reflects a deep truth: the ring represents the natural world,, while the seal represents Shabbos/above nature- the awareness that all of nature belongs to Hashem. The seal is not separate from the ring; it’s part of it and transforms the whole ring into something marked by its owner. So too, our everyday, natural life must be permeated with the “seal” of mesiras nefesh—the mark of miracles and total connection to Hashem. 

That’s why marriage is done with a ring, learned from Yehuda and Tamar, because marriage itself blends the natural and the infinite, bringing Hashem’s presence into the cycle of life. When we live with that awareness, our ordinary days become miraculous, our homes reflect Hashem’s infinity, and we help bring the world to its ultimate marriage - the revelation of Moshiach.