Sounds like bud blast to me.
Bud blast is the withering and dropping of buds from an otherwise healthy plant. Generally, the culprit is a rapid change in environment—usually going from warm to cold and vice versa. In the winter, frequent causes of bud blast are drafts from windows, blasts from hot ovens, and bringing a plant in from the car or outside. In the summer, it can be rapid heat fluctuations… In addition, some chemicals such as ethylene gas given off by ripening fruit can also cause bud blast and combustion gases. Could also be caused by low humidity or poor root system.
Funny thing, I just had 3 otherwise perfect flowers on Phal. Maki Watanabe fade and dry up at exactly the same time