Dishwasher Safe by MJ Etkind:
 
Alisi Latu is making a splash at the hottest new restaurant in Boston as an up-and-coming chef. By day, she walks among the landlubbers, but at night she is bound to the ocean, forced to transform back to her mermaid form and rejoin a thriving mer community.

For her entire life, Alisi has been running from the suffocating expectations of her mother. In order to start fresh, Alisi has swum far away from her home in the Pacific Islands to the other side of the world. Now, she is convinced that dating a human man will absolve her of the future her mother has laid out for her.

Sean McClary is the newest dishwasher at the restaurant, but he doesn’t seem to know how to operate the dishwasher. He is also living a less secret double fisherman by day and dishwasher by night. When Alisi swoops in to rescue the newest employee from a kitchen appliance, she wonders if he might be the human man of her dreams.