In just four lines, "Pearls" tells the story of two people who see each other in the things they make. He sees her dancing in his sand castles; she sees him in her painting, grinning through his stubble. Each has built something fragile or personal, and the other lives inside it as an image rather than a person standing there.
Then comes the loss. Both are "washed away," as if the tide takes the castles and the canvas along with the lovers themselves. The phrase "molecules of destiny" makes this feel less like a quarrel and more like something out of their hands, a force too big and too small to argue with.
The last line turns the poem hopeful. They return "as pearls of same oyester" (the poem's own spelling), suggesting they end up together after all, formed in the same shell. The mood is wistful but gentle: sadness at what the sea erases, and comfort in the idea that something beautiful can come from the same grit.