The phrase 'Tie The Knot' is used to indicate that a couple is getting married.
Example of Use: “Christina and Bill are about to tie the knot. The wedding is on Saturday!”
The origin of the term 'tie the knot' is unknown and ancient. What is known is that knots are used in many cultures to symbolize unbreakable pledges, and have been associated with marriage since at least the 13th century.