Maelstrom by Elsa Jade

The Intergalactic Dating Agency promised a bride from this small, blue planet…
As an ocean-dwelling Tritonyri warrior, Maelstrom Amyth sacrificed everything he loved in the centuries-long battle against the cruel and careless land-dwellers. So when he and his pod-brothers are sent to Earth to gently woo Intergalactic Dating Agency brides for his world’s survival, he’s definitely a fish-man out of water.
She thought the seas were deep and dark and dangerous, but then she looked to the Big Sky above…
Ridley Blake grew up in landlocked Iowa dreaming only of the ocean, but she washed out of Navy SEAL training after nearly drowning during a panic attack that left her with thalassophobia—the fear of deep water. She figures she’ll never dive again, until she is summoned to the middle of Montana under mysterious circumstances.
But the troubles they both left behind have bigger teeth than they knew, and now Mael and Ridley have to sink or swim together…