Looking for information on a book read decades ago.

Decades ago I read a book that I can not think of the author or title that I would like to reread.

I where of the seeming wrong but strong opinion that it was written by Huxley and it style strongly to this day remind me of Huxley works such as Island.

In any case, the plot is that for some unknown reason the world without warning divided into two with no women or female children in one reality and no men and male children in the other.

Right after this divide for example many fires broke out in the women world/universe/reality due to all the men disappearing and the women needed to try to deal not only with the shock of the event but fighting such large scale fires when most have little or no training is doing so.

This book was written at least four decades ago so there was no female firefighters at the time and only a few women with engineering training.

This went on for a year or so during which both men and women got used to societies without the other sex until the two worlds where once more merge without warning or reason given once more.

So does anyone know the author or the title of this book?