POWER

No one, simply no one should have enough power over someone to hurt them. Its a simple enough thing to say and believe, after all if someone has that much power, they basically have the power over all aspects of ones life.
Sadly humans are not capable of being sincere and yet not giving someone that much power over them, the truth is that few people can be trusted in this world, and anyone can hurt one knowingly or not, yet it is a need of humans to trust a few in this world.
This need for affection, love and friendship is what costs people the most, as it requires us humans to open up and trust someone, thus becoming vulnerable to all sorts of disappointments. This hurt is something that can affect the very personality of people, the very existence can be changed to core, because when people trust someone they pour their heart out and then all their weaknesses are out in the open. And it hurts the most when someone you trust uses your weaknesses against you.
So one should always try not to anyone give that much power to anyone. That power which can give someone an opportunity to play around with ones feelings. There is no one, that one can trust blindly, except for oneself because no amount of time of knowing someone, can bare their soul for one, and they can always turn on one at any moment.
Am i saying that we should never trust anyone, no, trust is important for any relationship in this world, even that of enemies. Thus one should be careful as to who one trusts.