Whats the deal between North & South Korean that they can't forgive each other and unite?

This goes back to the time frame of 1895 when the Japanese and Russians (pre USSR) were battling for control of the peninsula. Long story short, when the Japanese lost the Second World War in the Pacific the nation was again split at the 38th parallel. The 38th line is a natural split based on the Yalu River so it wasn't that difficult to decide at the time. Enter the North Korean invasion of South Korea and it was a Chinese assistance after the North Korean Communists invaded the South Korean nation ~ (following the conclusion of the Chinese Civil War that ended with the Communists under Mao in control in 1949 ~ Chiang Kai Shek was an idiot anyway) ~ the USSR didn't start providing supplies in the form of arms and so forth until after Mao had made a trip to Moscow after the war had started.

Anyway, one must be careful not place European standards to a nation on the Asian Continent that has been ravaged by many. You may as well ask "Why the Chinese, Koreans, and Malaysians still hate the Japanese today?"

Edit: Being a Democracy or being a Communist nation is more than mere "words" as they have become largely in the United States today. Today, many people simply no longer see the difference. In this part of the world it is the very fiber of existence to which Democracy means something to people. I would at this point suggest you pick up a book entitled "Coldest Winter" by David Halberstam and read it. Along the way attempt to understand through your local library some of the History of Korean Peninsula. The answers you seek cannot be garnered in one answer here in this superficial forum. Dig deeper, discover, and then come back and share.

North Korea is governed by a Communist personality cult style government a through back to the days of Stalin. Problem #1, The Red Chinese, go in with a guns ablaze to unite the country militarily, you may have a 2 million man army of screaming Chinese coming down on you. China and North Korea have a love hate relationship. The Chinese will also feel threatened that a new power is on their door step, they like the communist north as a buffer guard. If you Are North Korean and you say you hate your government, well, here are your options: Shot....or jailed and shot, or Jailed, tortured and then shot. North Korea is a police state. Lastly the guys holding the power in North Korea are not that willing to give it up. If you are a general in the North Korean army, live in a big house, have the best of food and clothes, have a car and servants....and power unspeakable are you going to give it up.

North Korea is a communist Country while South Korea is a capitalist country.The two political ideologies are eternally opposed to one another and that is why the two Koreas will never know peace until either both of them agree to adopt the same political ideology or if the North conquers the South or vice-versa.

east & west Germany only reunited when the east gave up communism.

communism works best under a totalitarian regime & so communism & democracy can't live together under the same roof.

as long as North Korea has a dictator & as long as the North Koreans are content to live under a dictator, they will not be reunited w/ South Korea because the South Koreans have no interest in living under a dictator.