I love this family!

Since the other one hates each other's guts.

Hardly. UK have the same Language and Alphabet, the same type of (capitalist) government and most importantly are in a Union.
Asean all speak different languages, and use different alphabet from each other. They also have different governments with Japan and S.Korea being "Capitalism" and China and N.Korea "Communism."
England didn't betray the others in WW2 like Japan did the to Korea and China.
Chinese and Korean people still despise Japan for it.
In major sporting events, for example during the Olympics Football semi-finals between S.Korea and Japan, they committed more fouls and the tension was obvious.
Hetalia sure likes to twist reality and keep events vague.
Then again England is the only canon character from UK family.

They're more of an official family.

0w0