Couples that act like best friends and lovers last longer?

"Act" no. Are, yes.
Too many get together's are Lust at first site. The site that allows them to enjoin with their Lustful desires does not make for a lasting relationship.
Love at First Sight is really what many get.

couples that ARE best friends and lovers last longer ---- acting is fake it means their feelings are not real

true....you can't find someone who knows you more then the person who knows you best....