Why did Solange Knowles violently attack Jay Z inside an elevator of The Standard Hotel on the night of May 5?
We may now have a partial answer.
According to a People sources, Knowles was "provoked" by designer Rachel Roy earlier that evening, with Beyonce stepping in to tell Roy "not to talk to her sister."
Jay remained silent during that initial confrontation.
Roy has known the Knowles family for years and is actually the ex-wife of Jay Z's former business partner, Damon Dash.
She was also a guest over the weekend at Kim Kardashian's bridal party.
Toward the end of the night, "Jay said something inappropriate to Beyonce and Solange, and she snapped," says the insider.
"When they got in the elevator, it escalated quickly the way family tensions can [and] got exceptionally heated the way family moments can."
That much is clear to anyone who has seen the full Solange assault footage:
It remains unclear, of course, just what brought on the argument with Roy and why Solange would get SO angry at Jay Z for simply remaining uninvolved in this alleged argument.
A witness, meanwhile, claims Solange was drunk at the time of the beatdown - but People's insider says the artist "was not intoxicated" and has already moved on.
"She's fine now," the source says of Solange. "She's back home in New Orleans and she's going on with her business."
Other theories on why the beef erupted include ...
We may never know for certain what caused her to snap like that, but hey, at least we'll always have anonymous sources giving us their best guesses.
And these #WhatJayZSaidtoSolange memes: