The story
Originates from the 1549 Book of Common Prayer, with the original wording being "till death us depart" (using the obsolete “to separate, part” sense of depart).
Etymology from Wiktionary, CC BY-SA 4.0.
till death do us part
Today it means: Until death separates us; a common phrase stated between the bride and the groom at a Christian wedding, indicating a commitment to their union. Full definition →