In all 3 cases, it was well over a year LATER when I asked them, "Please, just tell me WHY ...
By which I meant, a year or more after the breakup. None of these women dated me for a year or even close to it.
But that doesn't detract from your point at all. They just decided, suddenly, they were no longer attracted to me, and you're quite right:
Once a woman decides she is no longer attracted to you, it's all over, and there's nothing you can do to change her mind.
I have several divorced friends and, from their perspective, it was quite sudden. The real story, however, was that they were not observant of the signs.
Most women will keep up a facade of still being interested, as the interest slowly fades. It's when the declining interest level finally crosses the point-of-no-return threshold, that the guy finally sees it, but it WAS building for a while.
You have to be alert for the signs that "she's lost that lovin' feeling". She won't tell you until it's too late