This was a very prettily written story. I wouldn't necessarily call it a romance, though - while there's a romantic relationship in the story, to me it felt like everything was more about longing than actual love.
Meriel spends her days doing what her mother taught her to do, what her grandmother taught her mother to do. They keep an army of sea creatures-turned-human led by an angry god from destroying mankind. It's a noble goal, but a lonely one, since Meriel is as trapped as the monsters.
A seal manages to slip through her magical net one night, and is sent to plead the monsters' case to Meriel, to ask for their freedom. The visits start to challenge everything Meriel thought she knew, until she's unsure of what it is she's supposed to do.
To release them is to doom humanity, but Meriel wants more for her life than dedication to the nets.
In the end, it's longing that does in both Meriel and the beasts, but that longing also sets them free.
The book got bonus points with me for including a selkie. <3