Sometimes when a watermelon vine has 2 or 3 good-size fruit on it, that is all that it can handle, and it will abort any other developing fruit. That is my best guess as to what is happening on your plant. Stressed plants will also abort fruit — check if the vines and leaves look healthy or show any signs of disease or infestation. Make sure that the plant has plenty of water and enough nutrients. Poor pollination can also cause fruit to drop before maturity.
Sometimes when a watermelon vine has 2 or 3 good-size fruit on it, that is all that it can handle, and it will abort any other developing fruit. That is my best guess as to what is happening on your plant. Stressed plants will also abort fruit — check if the vines and leaves look healthy or show any signs of disease or infestation. Make sure that the plant has plenty of water and enough nutrients. Poor pollination can also cause fruit to drop before maturity.