Most Helpful Girl
People date after break ups. I'm not sure why you'd think there is something wrong with your ex trying again with someone new. And he might not have been a rebound. She could have really liked him at a time only to realize her feelings are stronger for you.
Most Helpful Guy
I'm personally of the opinion that people have exactly one and the only chance.
If they feel like breaking up despite you have given them the most you could what makes you think it will be enough the next time?
It's pointless, she will come back because she feels lonely right about now but will dump you again when the tiniest opportunity arises.