Weddings should (supposedly) be the happiest day of anyone's life, which means that there are tons of traditions and superstitions around engagements, build-ups, planning it and that's before you even get to the big day itself.
For example, traditionally an engagement ring should be bought with at least three month's salary of the proposer.
It's an old-fashioned rule and is pretty much a non-goer in 2022 thanks to the spiking costs of pretty much anything and everything.