Rules are rules

That night when he walked into the club, was shocked to see some beautiful women there for the first time.
"why? what happened to our so-called tradition & rules?" he demanded the secretary.
"We have decided to allow members to bring in their wives once in a month for dinner and dance" was the reply
"but that is not fair! " he complained, "I'm unmarried.... can I bring in my girl friend?"
" I think that can be ......" secretary though for a moment, then added ".... allowed, provided, she is the wife of any member..."​