It's a myth, an empty phrase milled over and over by loquacious dimwits.
When it comes to personality, birds of a feather flock together.
Proceedings of the National Academy of Sciences, 7/2003 wrote...
In Western society, humans use neither an 'opposites-attract' nor a 'reproductive-potentials-attract' rule in their choice of long-term partners,
but rather a 'likes-attract' rule based on a preference for partners who are similar to themselves across a number of characteristics.
/thread.