Like a magnet, polar opposites attract.
Differences and opposites pull, attract and draw together while samenesses and similarities
push away or repel from each other
So opposite people
fit together and identical people don't mesh together, according to the expression.
Guy: You two are nothing alike. I don't know what you see in him.
Girl: Opposites attract.
Guy: If that were true then rich dudes would
like gold diggers
Girl: Who said they didn't? Other girls?