Why do dumpers get jealous after finding out that the dumpee is dating someone new?

[Anonymous]

I have seen this and have also gone through this myself, being the dumper even a year later after I dumped my ex and finding out that he started dating someone new I did get a little jealous, don’t really know why and we haven’t talked that whole year. As a dumpee, after I started dating someone new, a dumper ex got jealous and started reaching out. Why does this happen? Share your stories too if you have any. It seems pretty common too

[Mister_E_Alaska]

It's best told with a toil I use in my life when dealing with others and control issues.
We all go through life with a picture of how we see things ending. Driving to work, mel planning and going on a date. You hope that if you do X Y will happen at the end. Humans can have a really difficult time when Y doesn't happen even though they did everything right in their head. The longer then plan of X was the most they're invested in Y. Suddenly Y isn't what's going to happen but it's because of someone else's choice.

[Ephemera1]

They want to feel as if they can't be replaced.

[OpenWine]

underestimating the "trash" you just threw out