Why did my ex move on so quickly?

Such as, if your ex moved on fast because they never actually loved you;

I know from my own “misadventures” in love, that my ex’s were able to move on quickly because they were more attractive than I am, and far less shy, and sometimes because they were far less picky than I am.

or if they moved on quickly because they were secretly starting up with their current person before you broke up;

Why cant I breathe when I sleep on my back, I can breathe if im on my side or stomach but I feel uncomfortable since either my neck is twisted or my back is in pain, im physically healthy and my surroundings are clean so whats the problem?

Different tack: I don’t think you asked what you want to know, you asked what you’ve heard other people ask.

or if they moved on fast because they can control their emotions like a simple light bulb;

What I suspect you really want to know, is one or more specific questions.

Why is Tiananmen Square censored?

Of the ones I was able to talk to about it all rationally later, some of them admitted they “used” a new “hook up” the same way some people use drugs, to dull the upset over our breakup; some said (perhaps as revenge) that I was easy to replace; some said they just got lucky. Most didn’t stay with the quick replacement, but a few even “panic married” the replacement, as part of being upset about the breakup.

and so on.