How do I change my Facebook relationship status without my Facebook friends knowing?

change the visibility to "Only Me" first, then change it. If you dont do that your friends Will see it.

If you want your facebook friends to stay out of your business with your relationships go to change your status and click on the blank line. You will no longer have any relationship status on facebook. Nosy people will be nosy, but it gets rid of that "only official once on facebook" stress people put on relationships. You can do that with almost any info facebook wants. Also, you can hide that post from your timeline if you would like by going to your profile and hitting the top right corner of the post. Or go to settings and change your privacy options.

When you post it, go to the post that says "______ went from being ..." and delete it. Or change it so only you can see it. I believe there may also be a privacy setting so where it doesn't post it but I am not up to speed on that.

Change it to being in a civil union Works every time

you have to be kidding me