it's proven that only immature people ''fall in love'' and no way in hell someone is going to tell me that 2 people are destined to be with each other, the grass is supposed to be greener on the other side of the fence otherwise our species would have slim chances of survival
marriage, 2 people staying together for life - it's all artificial and planted into our brain like a virus since day 1

Ok, are you saying that the grass is supposed to be greener on the other side, or are you saying that it isn't? You have a run on sentence and didn't specify.
The grass for the most part is never greener on the other side. We all think that, and we usually find out that we are wrong. Many times it is is just as "green" or far worse.
Maybe your perception is skewed due to the influence of the Baby Boomer generation, which had an explosion of divorces? Or this trend of everybody has to be happy all of the time, so when a person in a marriage is "unhappy" or "bored", they want a divorce (so that they can be happy or "have fun")? It seems that many people today are stuck in a perpetual adolescent stage, and when forced to "grow up" or face challenges (like putting aside their selfish desires) they cannot handle it.