The condition in which someone you like gets into a relationship with someone else, which then leads to stalking your crush's significant other's Facebook page, usually in sadness and narcissism.
"My girl got together with another guy. I went through his Facebook page to see how horrible he is."
"Dude, I think you have Facebook Jealousy Syndrome."
"Dude, I think you have Facebook Jealousy Syndrome."
by Judennan July 12, 2014