
There are several species in this manhwa, one of them is the fae/fairies, who lost their first prince and rightful heir 2 years ago (he mysteriously disappeared), so the fairy royalty is having tensions with who will succeed the throne. (This is only briefly mentioned.)
The humans are concerned because if the next Fae ruler hates humans, that could stop trade of magic tools to the human kingdom, and may even start a war (?). If I'm not mistaken, the first prince of the Fae was quite sympathetic to humans, but now he's gone.
This is why Nadia proposed to Abigail at first-- the mermaids are on good terms with the Fae so if the mermaids had a human Queen, the Fae would have to be friendly with humans.
im 100% sure that verite is the lost prince that disappeared from the fairy kingdom cause it makes sense its been 2 years since he has been in that mirror and 2 years since the prince disappeared