...

He is north, She is South
He is a negative, She is a positive
He is a dragon, She is a snake
He likes salty, She likes sweet
He likes fat, She hates fat
He does things slow, She does things rush
He is a perfectionist, She is an average
He is organized, She is a mess
He plans things ahead, She plans last minute
He is a busy bee, She is a lazy pig
He never rest, She is resting all day long
He is casual, She is formal
He is tight, She is jovial
He is logical, She is emotional
He is calm, She is a panicky
He likes bright shirt, She likes dark shirt
He eats the noodle, She drinks the soup
Dunno why they united, but perhaps because they complement each other.