How could a girl move on so quickly after breakup than a guy ??

There can be different reasons. It's true that sometimes the relationship was over in her mind before it actually finished and so she doesn't really have anything to get over. It can also be true that she hasn't actually stopped to process the loss yet and is just living off the "grass is greener" feeling until she realises that it's actually not. Equally, she might be suffering more than you know. You never know what someone is feeling behind the scenes. Appearances can be highly deceptive.

What is all important in one sided breakups is what you do now. If she is not completely convinced that things are over, she can be quickly convinced if the guy makes the wrong moves and doesn't give her the space to miss him. If he tries desperately to cling on he often just seals his fate.

It depends. She probably was emotionally removed from the relationship before the breakup.

In my wife's case, there were four men for every girl at her college, so there was no gap between her fwb's.

They have more opportunities

Most women have mentally moved on from their current bf before they actually break up with them.

Girls grieve the end of a relationship before it actually ends

She had looooonngggg been detaching herself. Girls go through heartbreak just like we do. We're human and have feelings

We don't break down if we aren't attached and emotionally invested

🤔 in my case I was exhausted by the BS long before we actually broke up or he did something so bad it flipped my ‘give no more fucks’ switch.

It may not have been quickly... she may well have been over it for much longer than you knew.

Depends on circumstances. Who initiated the breakup? Usually the imitator of a breakup has already been processing their feelings of the relationship ending before the end ever came.

There's also people that tend to be codependent and need someone so they move on quickly.

There's also people who use someone as a rebound outlet.

There's really add many different reasons as there are people.

Or sounds like you maintain a lot of girl vs guy stereotypes. If you want to understand people, you will have to set those aside.

I've usually gotten over them before the breakup

You’d be surprised.

The thrill is gone

Her feelings for him were dead.

Or she’s just dead inside and feels nothing for anyone.

You got to be kidding me how quickly does a guy get in bed with the easiest skank