Excellent shot. I like the transition of going light from the top to a darker bottom. It brings out the effect of the sun and highlights the children. Also, you must have given them a huge bribe to be holding hands. That simple but emotional scene of the two children, holding hands, walking along the beach, makes this picture's story. Your composition is very well done.
The reason why the sun sets in the evening is because it wants to see the sunrise in the morning. I rise in the morning because I want to see them both. RvdB