Where did the conflict rise from?

Conflict arose the day a single celled organism split into two distinct copies. It divided until there were no resources left and it consumed it's neighbour.

Ideal conflict point arises when you realise that you no longer benefit from the person you exist along with. The distinction between two parties becomes a growing chasm of contradiction, so contrasting that only one can exist, and another is heresy or anathema.

The inflection point of conflict can extremely minor, like a bucket (War of the Bucket) or even random bottle in a place where sun don't shine (Yugoslav war) or even a misplaced confidence of artificial harmony (Lebanese Civil War). It's simple inevitable.