"I'm not as good of a swimmer as you" says Bobby. "Especially not in your current form. Maybe we should go back to the beach?"
Katie agrees and the two of you swim back to the beach. The whole time you can't stop thinking about how awesome it is that your girlfriend is a mermaid. You both bodysurf a wave onto the sand and lay there for a moment staring up at the sky catching your breath from the swim. You view of the full moon is interrupted by Katie's smiling face, her wet hair cascading around it like a halo.
She leans in for a kiss and you wrap your arms around her, pulling her into a long and passionate embrace. You can feel her dolphin-like tail against your leg. Your hands slide down her back to where her skin begins to transition from her normal skin to the gray of her tail and she shudders a little. Your lips part and you see Katie smiling again. She takes one of your hands in hers and guides it from her back to her front, showing you her slit is still in the same place. You run your finger around her lower lips and she slides her tail over so it is between your legs.
You are so close to when a thought suddenly crosses your mind: werewolves can spread their condition through a bite. Surely weremermaids can spread their condition too, but how? As much as you desperately want to continue you're not sure being a weremerman is something you want. Maybe Katie knows enough about her condition to know what will happen?