Answer: Apple flowers can certainly be affected somewhat by growing conditions, the soil, the temperature and the weather, and they do often fade to a paler color with age, however it would be unusual for them to suddenly start out white.
One possibility is that the root stock has overwhelmed the grafted top of the tree, this could cause two different colors of flowers or change colors and would also result in the tree setting different (or no) apples.
I would suggest you consult with your local Cornell county extension to try to determine what is happening to your tree. They might appreciate photos of the overall tree to see the pattern of the flowers. You might also run some basic soil tests to make sure the soil is optimal for growing apples. Then based on the test results you could make any needed changes.
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