A mental health condition triggered by *not* experiencing what was perceived to be The Best Time Ever. Often abbreviated as PFSD. The word "Fomatic" is derived from the Millennial acronym FOMO.
Instagram and Facebook are the most widely-cited trigger-sources due to their excessive aggregation of photos documenting: birthdays you weren’t invited to, evenings you chose “getting a good night’s sleep” over going out, beach days, weekends away, impromptu rooftop hangs and parties you did not attend because you were only going to go if that guy you liked was going but he RSVPd “no” on the invite so you were like what’s the point, but then found out he went.
PFSD is often strongest when you leave just before something good happens.* An excerpt from the article Should I Go Home, A Guide:
Leave too early and you could miss The Night. The Night occurs on rare, magical occasions, like shooting stars, leap years and Kanye West’s rants on Twitter. The Night happens like love and lactose intolerance — when you least expect it — which makes it hard to effectively prepare. You know The Night: your crew almost didn’t go out. Everyone wore sneakers and the kind of sauce-stained gym clothes that double as pajamas when laundered. You go home because you’re a little tired, a little sober, a little bored.
Then half an hour later Bill Murray walks into the bar, buys everyone shots and starts a disco on the dance floor.
To use in a sentence:
Armadilloface: Are you ok Touphana? You look like you’re about to throw up.
Touphana: No, I just had a PTFD flash black to the time I saw that photo of my best friends laughing without me on Instagram. I think I might faint.
*It should be noted that those who ghost very rarely experience PTFD.