Sometimes as steads... when you know each other too much... observe too much... the flaws sometimes just come out...
The weaknesses and the bad points will be noted very strongly... cos he/she doesnt like it...
so... i think its rather not good to know each other too much...
cos after that the liking may sour...
but perhaps all these are just redundant if both of them take their time knowing each other...
hmmm... point taken.