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So, what led Solange Knowles to attack Jay Z as big sister Beyoncé calmly stood by during the longest elevator ride known to man? Amid the Internet sleuthing (Solange allegedly deleted all but one Beyoncé photo from her Instagram, only not really) and body language experts (she's probably tossed a hissy before) over the insta-viral surveillance video from a Met Gala afterparty come some more substantial theories on what seemingly led Solange to hit, kick and throw random objects at her brother-in-law.

First up is the London Daily Mail, which believes it was a professional crisis that triggered the tantrum.

"Solange is so angry because Jay Z promised to give her more help with her career, and when she brought it up again the night of the gala, he told her he just didn't have the time to work with her in the studio," alleges a source. "Solange wants a major career like her sister, and she's tired of living in her shadow. She's jealous. Jay Z promised he would help take her to the next level but he never found the time to keep his word. Enough was enough for Solange! She flipped out and screamed at Jay Z that if he didn't want to help just say so and [stop] pulling her chain!"

Solange, who supposedly also had an argument with designer Rachel Roy at the Met Gala, has an album due this year.

Meanwhile, the New York Daily News says tempers flared during the post-Gala shindig at the Standard Hotel when Jay announced he was going to hit Rihanna's afterparty sans Beyoncé. The spark, however, purportedly came a few minutes earlier, courtesy of some Solange pals.

"Two of her friends, who were not dressed for the Met Ball, showed up at the Standard and caused a scene downstairs," alleges a source. "They wouldn't leave and kept name dropping Jay Z. They were pretending they were guests of his and not hers."

When Hova found out, says the paper, he told Solange, "Don't use my name." She then "turned sullen and said she wanted to leave the party."

At that point, Jay revealed his plans for RiRi's bash and Solange supposedly lost it.

According to a spy, "She said, 'Why can't you go home?' and to Beyoncé, 'Why does your husband need to go to the club right now?'" Jay allegedly replied, "You're one to talk."

And that's when the altercation supposedly began.

People, meanwhile, has its own take on what went down.

"Jay said something inappropriate to Beyoncé and Solange, and she snapped," explains a source. "When they got in the elevator, it escalated quickly the way family tensions can. It got exceptionally heated the way family moments can. … Solange is super-protective of Beyoncé."

The insider insists that she "was not intoxicated," adding that she was also "provoked" by Roy.

"Solange has flipped her lid like that before," a source tells Us Weekly. "She is genuinely a sweet and nice person, but she also keeps s--- real. She can take a small thing and it triggers her. ... That's why Bey and Jay were so calm. They are used to this from Solange."

Bey and Jay tried to quell furor over the dust-up by putting on a smiley united front Monday night at a Brooklyn Nets game. As for Solange, she joined Jay on a jewelry store run/damage control opportunity in New York on Tuesday, reports TMZ. The two quietly browsed the women's wares at Mr. Flawless but didn't buy anything. They "showed no signs of strife." Mr. Flawless, however, denies they were in his shop.


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