A joke relationship status on Facebook made after a serious one has just been terminated. This makes it so one's status is not set to nothing (or worse to "Single"). Common BFR's are: It's Complicated with, Married to...ect. They are usually set around one to three months, until the person can set their status as "Single" shamelessly.
Yeah, well Mary and Jack broke up. So I think it's just her Buffer Relationship Status