You may have heard of the book and movie "he's just not that into you". It's so hard for women to see the truth and tear themselves away from jerks sometimes that they had to write a book to point out the obvious. In fact, no need for me to explain any of this, if you're a woman then you'll know better than me how difficult it's to pull yourself away from a jerk that you like.
However, what's even more interesting or strange is that many women I've spoken to don't have nearly the same difficulty emotionally when breaking up with a boyfriend they find boring or if they're lost respect for the guy.
In other words if you're a guy you're more likely to be dumped for being a loser than for being a jerk to women.
Ok, so this doesn't seem to make sense, but if you've read some of the older posts on this blog you would understand that much of what we do in relationships isn't driven by logic and conscious thoughts, but by our instincts that we inherited and evolved from cavemen days.
In cavemen days, survival was the key. So women would pick the fittest males, the weaker ones would be more likely to die from getting eaten by predators, or from inter tribal warfare. Nice isn't part of the equation, survival was. So if her man treated her badly and she immediately left the man, then there was serious risks to the survival of her and her children.
Therefore the body (or a woman's genes) have a built in mechanism that avoids this. It makes women more emotionally attached to men they think are stronger, even if those men are jerks.
Men that don't show much value however are easier to dump, even if they treat a woman better because they aren't seen as possessing as much value.
The emotions that make leaving a jerk so hard is just part of a woman's natural instinct to get the best genes from a man, and also to ensure her survival. In the modern world however, it means that women are often emotionally attached to jerks who they logically don't want to be with, and require a book and a movie to point out an otherwise relatively obvious point.