I sure wish that I could see the whole trunks. They aren't staked, are they? I doesn't look like they were pruned to create a good scaffolding for fruit when they were very young. And it might just be the angle of the image, but the trees look like they are planted in a pit.

Excess fertilization is a fairly common reason why fruiting trees may decide not to flower, but to put all of their energy towards vegetative growth.

Yes, it is odd that they would bloom for awhile and then stop. Maybe your local USDA Cooperative Extension Service branch office can help.

Do they get any flower buds? Could something be eating them? Various birds can strip apple buds.

I am far from an expert, but they do look like the branches need thoughtful pruning. Seems like they pushed out a lot of new growth too -- may be a sign of too much or unneeded fertilizer.

The ground is fairly flat, no pit. They were staked for 3 years, now they aren't.

And they didn't get any flower buds, just leaves directly.

For fertilizing, I am using organic fruit fertilizer at the start of the season and then again later one more time during the season.