In some cultures, it is customary for newly married couples to jointly make the first cut in a 'wedding cake'. What is the origin of this tradition?

One source says it dates back to Victorian times [1], another to the 1950s [2]. But in yet another article that actually explores the history of wedding cakes in Western tradition in great detail with sources, the date is set in the 1930s [3]. This is when couples reportedly began making the first wedding cake cut together as ceremonial act, with the actual cutting and distribution of the cake pieces being done behind the scenes. Prior to this, it may have been the job of the bride to cut and distribute the cake to everyone without the groom's assistance.

Incidentally, the quintessential tiered wedding cake is thought to have been popularised by Queen Victoria's massive three-tiered fruitcake weighing over 100kg and measuring about 1m in diameter. As with any tradition and cultural meme, such traditions would have spread through influential pioneers like this.

This is all to say nothing of other cultures outside the Western white wedding tradition, where cake may play an even more central role with different traditions.

[1] https://www.theknot.com/content/cutting-the-cake
[2] https://www.tenutalavalle.it/en/cutting-the-cake-meanings-history-and-ideas-for-making-it-a-memorable-and-iconic-moment/
[3] https://www.mercatornet.com/the-history-and-significance-of-the-wedding-cake