Simple!
Because they want to!
Again, they would like to have you miserably polarized on them, rather than seeing you happily move on.
Your ex wants you to be miserable without them.
When they say “No, really, I am happy for you…” does that sound sincere?
Does it look like what they are saying is backed up by a profound emotional realization?
Do they mean it?
Very often, they are trying to fake it!
They rationally know this is the right answer but they are often hurting inside.
Why? Because a break up is the death of something.
It is the end of that chapter of your lives.
Some people are able to easily embrace change and move on.
Some others want to keep things where they are and repeat the same scenario over and over again.
Yes, but they are the ones who broke up, so why is it that they don’t move on with that?
It is because they face an internal conflict.
Often in their minds, a part of them still wants to experience some of the feelings and emotions they had with you.
They build up romantic fantasies on the ruins of your past love.
It is a competitive thing as well.
A part of them wants to believe that they are better than the people you are dating now.
Being able to trigger your sexual desire is a victory for them.
They want to bring you back to that space even though they know they will shamelessly reject you once they bring you there.
See how it works?
I know, it contradicts itself and it is not logical!
But who talks about logic???
These are instincts.
They are animal needs that have been developed millions of years ago in the human mind.
The logical relationship boundaries came way later.
I know we are getting a bit side tracked here but this is why so many people cheat when given the opportunity.
It is because of our animal instinctual nature which is still embedded in us.
When given the opportunity to procreate, nature programmed us to go for it!
This is why for many people the instinctual animal drive overpowers the logical alternative.
More on this on my site… It’s vast chapter.