Few people instinctually grow or seek to hate somebody without reason, and most other people could care less in the case they do. The one close second we can find is lust, often confused with love and sometimes indistinguishable from eachother. There is always drama, emotional conflict and dealings with other people. Things never come easy and the world has ways of blocking a person from what they desire, even when it is due them. Love is often rejected or even if requited, other factors come into play which prevent an easy fulfillment.
Desires are often out of reach.
Despite what the ramifications are of playing out such drama, it will still be followed because to not do so would be an even greater emotional loss. When all is said and done, the drama must end as all things, in death. It is the final culmination of life and the point which all history is written in stone and unchangeable. Spurned lovers seek to die, lovers seek death to seal their emotions for eachother. It is the one thing that is the hardest to overcome.