Open Relationship ?

I saw  someone declare they have an Open relationship. But when I found out what is their logical reasoning, I literally facepalm myself.

Quoting that fellow(not revealing the sexes here):
"So , I am coupled with my partner and everybody knows bout it. Which leads me to think, since this is an open secret, which means now I am having an 'open' relationship right?"

Seriously, that moment, I really had the urge (and I did ) to tell that fellow the mistake that he/she had done.
Declaring an open relationship in cyberspace is like announcing that you have a sex buddy in public space.

So imagine a dude yelling ,
"my relationship with this girl/ guy is only  sex related, nothing else!" 
What would you think of him? Or her?

I understand that in urban areas, having an open relationship is rather common, but it takes either a casanova or Paris Hilton to announce it.
Not saying I am grammar Nazi or anything, I am just against the mistake made pure  ignorance.

Yup , this is a first world problem post. But I am so bored now that I have to do something to avoid myself from sleeping

Cheers
Boon