The most probable cause for the problem you are describing is related to pollination. Cantaloupe has female flowers as well as male flowers. Transfer of pollen by bees from male flowers to female flowers must occur in order to have fruit. Environmental conditions as well as nutrient imbalance can influence fruit set. Hot temperatures and/or high fertility may cause only male flower production thus no fruit set. On the other hand, cool and rainy conditions will impair pollination resulting in poor fruit set resulting in abortiveness of the fruit and early drop.

Often times, diseases and/or insects can lead to cantaloupe fruit to turn color and drop off. Root knot nematodes could stress the vines resulting in proliferation of blooms but no fruits. Crop rotation with kale, cabbage, mustards or marigolds is helpful.

The other issue is with micro nutrient deficiency, primarily lack of boron. Boron is essential for pollen germination and pollen tube elongation and penetration greatly influencing the fruit set. In case of incomplete pollination, where the fruit set has not been successful, the fruit may start to form than soon after turn color and abort.