Soldato
It's often because a relationship will have been emotionally over for a long time before they actually split up with someone. This is why it can be super confusing for a guy, to have a girlfriend lacking affection/not wanting to be relationshippy at all for a couple of months and acting all odd, then suddenly splitting up and being a perfectly romantic partner with someone new within days.
But yeah when all's said and done, BISHES BE CRAZY.
While I completely get this, it is not what I have experienced. None of my relationships ended lovelessly (so to speak).
I think it's more to do with this....
Its not just that, a lot of people (women and men) cant really function not in a relationship, they need someone, so they wont take long to move on when the last thing they should be doing is that, they end up just going from one relationship to another without really getting over the last one.