Unrelationship

A relationship between two people that cannot be classed as platonic but isn't officially a relationship. Not quite "friends with benefits".

"Sam and Lauren are in an unrelationship. They're totally doing it on the sly!"

unrelationshipped

The act of ending a relationship by changing one's relationship status on social media

I only found out I was single because Hayden unrelationshipped me on Facebook.