Make sure you are providing your violets with enough window-light and/or artificial fluorescent/LED light.

Well, here's the thing, I have been growing violets for over 50 years. Never had this happen before. Growing in my east window, have been for years. I water from top, they set in another pot, I look to see I don't drown them. Regular house temp, I live alone so temp is good for me, always has been alright for violets. They set enough buds, I just don't get why they dry up. Water is quarter strength fish fert, quarter african violet food, just plain water , and then start over again. Potting mix is fertilome potting soil, I've used it for years. I even escaped having thrips this year. I am baffled. Mostly mature plants, I'm going to start all new ones.

Wow ... 50 years, you ought to be telling us what's wrong ...

Could it be that it's time to repot ?

Aegis I am lost. 50 years is a long time. So I guess your gonna have to do it the omitting way. Work down the ladder until you find the problem. Velleta

I would have suggested the humidity in the room is too low, but since you are a long time grower, I am kind of baffled. Could be a pH issue too, so maybe try re-potting as aegis said.