Vampire Marriages
Lilith explained to Emilia about how vampire marriages occurred.
Like every other culture in this world, in vampire marriages, one had to pay one's respect to the respective people, which includes: one's ancestors, parents, and the Vampire Queen herself. The couple pays respects and gets their blessings in return.
This is a part that usually happened at the very last when the actual marriage was done.
The marriage has a lot of ceremonies to be done before the vows are made and the groom and bride become husband-wife.
There are a series of ceremonies and its present there because vampires, in the Immemorial Era and before it, were beings who had a very long lifespan. Even though they were mortals, their lifespan was long and so, marriage was something that would become a good memory for them that would last their whole life.