The girls decide to go for a swim. Jeff was slowly getting used to the strange sensations of being a swimsuit, the feel of his girlfriend's body against him, as well as the water.
It felt surprisingly nice. The discomfort he'd felt when he'd first transformed seemed to be replaced by something else. Comfort, perhaps.
At some point, he becomes aware that she has got out of the water. He can feel the warm sun on his wet surface, while his girlfriend stretches.
"How are you doing there," she says when she's far enough away from the other girls.
I'm fine, Jeff thinks, but he can't really respond to her. All he can really do is cling to her body and experience the world as a swimsuit. "Well, I'm going to have a bit of a lie down now," she says while unfolding her beach towel.