I have 4 large plumeria in pots that have been proficiently blooming for about 7 or 8 years. One in particular is not blooming this year and the others aren't as plentiful as they usually are. I repotted in the early spring as I thought they were too root bound last year. The blooms had been sparser last year. They get sun from sunrise until late afternoon. Always in same location. I've never pruned them. And are they too close together now that they are so large?

Beautiful / Healthy looking ! Agree with "too close together".. let them breathe & expose to more direct Sun.

Perhaps your use of high nitrogen fertilizer has resulted in less blooms / More foliage?

Might want to try using a "Blossom Booster" supplement.

I agree they are definitely crowding each other.