It is a desire for something received, constantly and always from someone else, filling a need everyone had, be it with food, gifts, money, or affection.
We get addicted to those offerings, give back something else in return, to which they get hooked as well.
A man-made brand of clever negotiating, getting what we need in the name of emotion, nobody suspects or realizes it, of course.
The sub-conscience that man kind has, which fools everyone including ourselves, to our true nature.
This horrid concoction created by lies, evolved to suit our fancy, even now, you still have not a clue; "Love" is funny that way.